The population dynamics of an indigenous Psyllid Acizzia Russellae (Homoptera: Psyllidae )with special reference to the influence of the host plant Acacia Karroo
- Authors: Webb, John Warren
- Date: 1975
- Subjects: Homoptera , Jumping plant-lice , Insect populations , Insects -- Ecology , Acacia -- Karroo
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5894 , http://hdl.handle.net/10962/d1013415
- Description: The biology and ecology of an indigenous, non-pest insect on an indigenous host plant were investigated. The study includes a taxonomic description of this new species, an account of its general biology, monitoring of the seasonal fluctuations in numbers of the psyllid and its hymenopterous parasitoids, and a study of various aspects of the host plant, including nitrogen levels, water stress, leaf hardness, and the effect of cutting, in relation to spatial and temporal differences in insect population numbers. Natural enemies, inter- and intra-specific competition had very little determining influence on the population numbers of the psyllid. Temperature and humidity had little direct effect, but may have influenced the population dynamics via its effects on the host plant. Seasonal patterns in psyllid numbers followed fluctuations in nitrogen levels; statistically valid correlations were obtained between leaf nitrogen and psyllid numbers on individual trees at various times. These findings were supported by the results of preliminary laboratory experiments employing different fertilizer treatments. No effect of water stress or leaf hardness was clearly discerned. Cutting of trees altered the characteristics of the subsequent regenerative growth so as to allow massive psyllid infestations to develop, thus showing the tremendous importance of the host plant in determining population levels in this insect. Preliminary investigations of the nature and mechanism of this effect were conducted, and its significance is discussed. The relevance of these findings to modern concepts of regulation in insect populations and to principles of pest management is discussed.
- Full Text:
- Date Issued: 1975
- Authors: Webb, John Warren
- Date: 1975
- Subjects: Homoptera , Jumping plant-lice , Insect populations , Insects -- Ecology , Acacia -- Karroo
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5894 , http://hdl.handle.net/10962/d1013415
- Description: The biology and ecology of an indigenous, non-pest insect on an indigenous host plant were investigated. The study includes a taxonomic description of this new species, an account of its general biology, monitoring of the seasonal fluctuations in numbers of the psyllid and its hymenopterous parasitoids, and a study of various aspects of the host plant, including nitrogen levels, water stress, leaf hardness, and the effect of cutting, in relation to spatial and temporal differences in insect population numbers. Natural enemies, inter- and intra-specific competition had very little determining influence on the population numbers of the psyllid. Temperature and humidity had little direct effect, but may have influenced the population dynamics via its effects on the host plant. Seasonal patterns in psyllid numbers followed fluctuations in nitrogen levels; statistically valid correlations were obtained between leaf nitrogen and psyllid numbers on individual trees at various times. These findings were supported by the results of preliminary laboratory experiments employing different fertilizer treatments. No effect of water stress or leaf hardness was clearly discerned. Cutting of trees altered the characteristics of the subsequent regenerative growth so as to allow massive psyllid infestations to develop, thus showing the tremendous importance of the host plant in determining population levels in this insect. Preliminary investigations of the nature and mechanism of this effect were conducted, and its significance is discussed. The relevance of these findings to modern concepts of regulation in insect populations and to principles of pest management is discussed.
- Full Text:
- Date Issued: 1975
"Complexes of carbohydrates with magnesium-ions" : "the isolation of an oligosaccharide containing L-galactose from the polysaccharide of Aeodes orbitosa" : "horizontal cellulose colum chromatography of sugars"
- Authors: Van der Linde, Michael John
- Date: 1974
- Subjects: Magenesium , Ions , Carbohydrates , Oligosaccharides , Polysaccharides , Chromatographic analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4504 , http://hdl.handle.net/10962/d1013282
- Description: Sugar complexes with anions and cations are reviewed. Evidence is presented for the formation of a complex of stoichiometry 1:1 in aqueous solution between methyl-α-Dglucopyranoside and magnesium perchlorate. The complex may be detected by the method of continuous variations. Measurements of changes in the proton chemical shifts of the glucoside in dauterium oxide, indicate that the complex is probably formed between the vicinal hydroxyl groups at C-2 and C-3 of the pyranoside ring and the hydrated cation. At elevation temperatures there is evidence for the presence of a complex of stoichiometry 2:1. Experiments conducted on cellulose indicate the possible formation of cellulose - magnesium-ion complexes . These complexes provide an explanation for the "protective action" of mEgnesium compounds on the cellulose portion of pulp during alkali-oxygen bleaching.
- Full Text:
- Date Issued: 1974
- Authors: Van der Linde, Michael John
- Date: 1974
- Subjects: Magenesium , Ions , Carbohydrates , Oligosaccharides , Polysaccharides , Chromatographic analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4504 , http://hdl.handle.net/10962/d1013282
- Description: Sugar complexes with anions and cations are reviewed. Evidence is presented for the formation of a complex of stoichiometry 1:1 in aqueous solution between methyl-α-Dglucopyranoside and magnesium perchlorate. The complex may be detected by the method of continuous variations. Measurements of changes in the proton chemical shifts of the glucoside in dauterium oxide, indicate that the complex is probably formed between the vicinal hydroxyl groups at C-2 and C-3 of the pyranoside ring and the hydrated cation. At elevation temperatures there is evidence for the presence of a complex of stoichiometry 2:1. Experiments conducted on cellulose indicate the possible formation of cellulose - magnesium-ion complexes . These complexes provide an explanation for the "protective action" of mEgnesium compounds on the cellulose portion of pulp during alkali-oxygen bleaching.
- Full Text:
- Date Issued: 1974
A contribution to the biology of Pseudodiaptomus hessei (Mrázek) (Copepoda : Calanoida) in Lake Sibaya, South Africa
- Authors: Hart, Robert Clynton
- Date: 1974
- Subjects: Copepoda -- South Africa Freshwater biology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5854 , http://hdl.handle.net/10962/d1012210
- Description: Aspects of the biology of the calanoid copepod Pseudodiaptomus hessei are described, with particular reference to its vertical migratory behaviour. The present investigations were carried out largely by means of Nansen-type plankton nets, but several new pieces of apparatus were developed and. are described herein. The daytime vertical distribution of P. hessei varies according to developmental stage and depth of water. In shallow areas of the lake the entire population is benthic or in very close association with the lake bed. In the deepest part of the lake (40m) the naupliar and early (i.e. C I - C III) copepodite stages are essentially pelagic, but the adult and late (i.e. C IV - C V) copepodite stages are predominantly benthic and may be quiescent or infaunal. During the hours of darkness, the calanoids are distributed through the water column. The nauplii are consistently abundant in the surface waters but the distribution of the other stages is not regular. The distribution can be related to lunar intensity in many cases, with the post-naupliar stages frequently occurring deeper in the water column on bright moonlight nights and in the surface waters on overcast moolnless nights. The dusk ascent and dawn descent of the calenoids is clearly related to changes in light penetration in most individuals. The movements of a fraction of the adults occur in the apparent absence of adequate light cues. This behaviour is shown more extensively by the adult females. An endogenous activity rhythm has been shown in the species under laboratory conditions and it is suggested that this may play a part in the migratory movements. A basic examination of the feeding methods, feeding appendages and food sources of adult and late copepodite stages has been made. Changes in feeding intensity through twenty-four have been examined in the field and under laboratory conditions. Using as an index of feeding intensity, the proportion of animals with food in their guts, it has been shown that a pronounced diel difference occurs in adult calanoids in the lake. Feeding is almost entirely restricted to the nocturnal presence of the calanoids in the water coloumn. This difference exists in the pre-adult copepodite stages, but is not nearly as striking. The absence of feeding during daylight is not readily accounted for in terms of food availability and it is attributed to the quiescent or possible infaunal existence of the adults. A periodicity in egg hatching has been shown Naupliar release from the parental egg sac is predominantly a nocturnal phenomenon in the hot and cool seasons. It is suggested that this may be important in attaining a favourable vertical distritution for the nauplii, and may be important in the distribution of the species. A preliminary acccunt of the seasonal cycle and population dynamics of P. hessei is given, based on data collected over two years at a single station. Seasonal changes in calanoid abundance are intermediate between those recorded in truly tropical areas and in temperate latitudes. Potential food sources show relatively little change. The vertical migration of P. hessei is considered in relation to its apparent ecological significance and comparisons are drawn with observations made on the same species or other pseudodiaptomids in estuaries and lagoons elsewhere.
- Full Text:
- Date Issued: 1974
- Authors: Hart, Robert Clynton
- Date: 1974
- Subjects: Copepoda -- South Africa Freshwater biology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5854 , http://hdl.handle.net/10962/d1012210
- Description: Aspects of the biology of the calanoid copepod Pseudodiaptomus hessei are described, with particular reference to its vertical migratory behaviour. The present investigations were carried out largely by means of Nansen-type plankton nets, but several new pieces of apparatus were developed and. are described herein. The daytime vertical distribution of P. hessei varies according to developmental stage and depth of water. In shallow areas of the lake the entire population is benthic or in very close association with the lake bed. In the deepest part of the lake (40m) the naupliar and early (i.e. C I - C III) copepodite stages are essentially pelagic, but the adult and late (i.e. C IV - C V) copepodite stages are predominantly benthic and may be quiescent or infaunal. During the hours of darkness, the calanoids are distributed through the water column. The nauplii are consistently abundant in the surface waters but the distribution of the other stages is not regular. The distribution can be related to lunar intensity in many cases, with the post-naupliar stages frequently occurring deeper in the water column on bright moonlight nights and in the surface waters on overcast moolnless nights. The dusk ascent and dawn descent of the calenoids is clearly related to changes in light penetration in most individuals. The movements of a fraction of the adults occur in the apparent absence of adequate light cues. This behaviour is shown more extensively by the adult females. An endogenous activity rhythm has been shown in the species under laboratory conditions and it is suggested that this may play a part in the migratory movements. A basic examination of the feeding methods, feeding appendages and food sources of adult and late copepodite stages has been made. Changes in feeding intensity through twenty-four have been examined in the field and under laboratory conditions. Using as an index of feeding intensity, the proportion of animals with food in their guts, it has been shown that a pronounced diel difference occurs in adult calanoids in the lake. Feeding is almost entirely restricted to the nocturnal presence of the calanoids in the water coloumn. This difference exists in the pre-adult copepodite stages, but is not nearly as striking. The absence of feeding during daylight is not readily accounted for in terms of food availability and it is attributed to the quiescent or possible infaunal existence of the adults. A periodicity in egg hatching has been shown Naupliar release from the parental egg sac is predominantly a nocturnal phenomenon in the hot and cool seasons. It is suggested that this may be important in attaining a favourable vertical distritution for the nauplii, and may be important in the distribution of the species. A preliminary acccunt of the seasonal cycle and population dynamics of P. hessei is given, based on data collected over two years at a single station. Seasonal changes in calanoid abundance are intermediate between those recorded in truly tropical areas and in temperate latitudes. Potential food sources show relatively little change. The vertical migration of P. hessei is considered in relation to its apparent ecological significance and comparisons are drawn with observations made on the same species or other pseudodiaptomids in estuaries and lagoons elsewhere.
- Full Text:
- Date Issued: 1974
A contribution to the limnology of Swartvlei: the effect of physico-chemical factors upon primary and secondary production in the pelagic zone
- Authors: Robarts, R D (Richard D)
- Date: 1974
- Subjects: Limnology -- South Africa -- Swartvlei
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5822 , http://hdl.handle.net/10962/d1007474
- Description: From Resumé: The effect of physico-chemical factors on the biology of the upper reaches of Swartvlei has been investigated during 1971-1972. Physico-chemical data have shown that Swartvlei was characterized by an extremely labile ectogenic meromixis. This instability was due to three factors : (1) the inflow of freshwater, (2) the inflow of sea water, and (3) wind stress. The magnitude of the effects of these factors upon the physics, chemistry and biology of the upper reaches was dependent upon whether or not the estuary mouth was open or closed. The phytoplankton of the pelagic zone of Swartvlei was dominated by nannoplankton. Three major categories were recorded: dinoflagellates, flagellates and diatoms. The major factor regulating their productivity in the upper reaches was light. As a result of humate staining and suspended detrital matter light conditions in Swartvlei were comparable to those in extremely eutrophic northern hemisphere lakes. A maximum integral primary productivity of 39.66 mg C m⁻² h⁻¹ was recorded in November 1972. The aerobic heterotrophic bacterial population in Swartvlei was usually less than 300 col. ml⁻¹ (plate counts). The activity of the total microbial population was measured with ¹⁴C techniques. Uptake of acetate was dominated by flagellates and one species of dinoflagellate when they were present. Glucose uptake was due to bacteria as was acetate uptake in the absence of heterotrophic phytoplankton. Glucose uptake was usually greatest in the anaerobic zone. This, and the presence of H₂S, suggested that a large active photosynthetic and chemosynthetic bacterial population may have been present in the monimolimnion. The possible importance of these bacterial processes in the total productivity of the pelagic zone of Swartvlei was discussed. Daytime zooplankton population size was statistically correlated with the size of the flagellate population. The zooplankton was dominated by Acartia and Halicyclops. These two animals were found in the anaerobic bottom of Swartvlei after October 1971. This corresponded to the disappearance of the flagellate population from the water column. The dominance of these animals in the zooplankton population may have been related to their ability to live in anaerobic water where the bacterial population appeared to be considerably more abundant than in the aerobic zone. Further implications of the results are discussed in reference to phytoplankton cell size and heterotrophy indicating a possible adaptive significance of these factors in Swartvlei.
- Full Text:
- Date Issued: 1974
- Authors: Robarts, R D (Richard D)
- Date: 1974
- Subjects: Limnology -- South Africa -- Swartvlei
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5822 , http://hdl.handle.net/10962/d1007474
- Description: From Resumé: The effect of physico-chemical factors on the biology of the upper reaches of Swartvlei has been investigated during 1971-1972. Physico-chemical data have shown that Swartvlei was characterized by an extremely labile ectogenic meromixis. This instability was due to three factors : (1) the inflow of freshwater, (2) the inflow of sea water, and (3) wind stress. The magnitude of the effects of these factors upon the physics, chemistry and biology of the upper reaches was dependent upon whether or not the estuary mouth was open or closed. The phytoplankton of the pelagic zone of Swartvlei was dominated by nannoplankton. Three major categories were recorded: dinoflagellates, flagellates and diatoms. The major factor regulating their productivity in the upper reaches was light. As a result of humate staining and suspended detrital matter light conditions in Swartvlei were comparable to those in extremely eutrophic northern hemisphere lakes. A maximum integral primary productivity of 39.66 mg C m⁻² h⁻¹ was recorded in November 1972. The aerobic heterotrophic bacterial population in Swartvlei was usually less than 300 col. ml⁻¹ (plate counts). The activity of the total microbial population was measured with ¹⁴C techniques. Uptake of acetate was dominated by flagellates and one species of dinoflagellate when they were present. Glucose uptake was due to bacteria as was acetate uptake in the absence of heterotrophic phytoplankton. Glucose uptake was usually greatest in the anaerobic zone. This, and the presence of H₂S, suggested that a large active photosynthetic and chemosynthetic bacterial population may have been present in the monimolimnion. The possible importance of these bacterial processes in the total productivity of the pelagic zone of Swartvlei was discussed. Daytime zooplankton population size was statistically correlated with the size of the flagellate population. The zooplankton was dominated by Acartia and Halicyclops. These two animals were found in the anaerobic bottom of Swartvlei after October 1971. This corresponded to the disappearance of the flagellate population from the water column. The dominance of these animals in the zooplankton population may have been related to their ability to live in anaerobic water where the bacterial population appeared to be considerably more abundant than in the aerobic zone. Further implications of the results are discussed in reference to phytoplankton cell size and heterotrophy indicating a possible adaptive significance of these factors in Swartvlei.
- Full Text:
- Date Issued: 1974
A study of the burrowing sandprawn Callianassa kraussi Stebbing (Crustacea - Decapoda - Thalassinidea)
- Authors: Forbes, Anthony Tonks
- Date: 1974
- Subjects: Estuarine biology -- South Africa Shrimps -- South Africa Decapoda (Crustacea) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5850 , http://hdl.handle.net/10962/d1011866
- Description: The distribution of Callianassa kraussi in southern Africa extends from Lamberts Bay on the west coast to San Martinho in Mocambique. This represents a northerly extension of the range from the previous known limit of Inhaca Island. In this area 59 localities were visited and records obtained for an additional 16. Three areas were selected for detailed study. These were the west Kleinemonde estuary, which is normally closed off from the sea by a sand bar and the open Swartkops estuary both on the southeastern Cape coast, and the Swartvlei system, which consists of a lake connected to the sea by a channel which closes intermittently, on the southern Cape coast. The nature of the burrows constructed by C. kraussi was investigated in these areas. Burrow complexes may have up to nine entrances but more commonly two to four. Laboratory studies suggest that the number of entrances does not exceed the number of prawns present and consequently burrow opening counts will give an estimate of population density. Water movement can result in the closing off of burrows while strong water and sand movement will exclude C.kraussi from an area. C.kraussi is also excluded from areas which have very coarse substrates. A three year regular sampling program showed that C.kraussi breeds mainly in winter/spring with a smaller breeding peak in summer. Egg development time at 20°C in a salinity of 35° /₀₀ is 30-33 days. There are two larval stages which last 3-5 days. Development time of the eggs is tripled at temperatures of 13-15°C while larval development time is extended to 9-14 days. Development is possibly slightly accelerated at 25 ± 3°C but the number of eggs hatching is markedly reduced. Larval development times were similar to those at 20° and 35°/₀₀. There are no planktonic larval stages. Growth was more rapid and greater size was attained in the open Swartkops estuary than in the closed Kleinemonde estuary. Prawns hatching in winter/spring breed for the first time in the following summer at an age of about 16 months and then again in the following winter/spring at an age of about 2 years. Prawns hatching in summer breed in the following winter at an age of about 18 months and then again in the immediately following summer. Longevity in both sexes is about 2 years. Dispersal is accomplished by migration of the post-larval juvenile phases at an age of 3-5 months. Non-selfmaintaining populations exist in areas where salinities are too low to permit breeding. Population densities were found to vary markedly in different areas. Investigations of osmotic and ionic regulation showed that C.kraussi is a strong hyper-regulator and thus distinct from any other known species in the genus. Volume regulatory ability is well developed and depends on variable rates of urine production. Salt loss in dilutions occurs almost equally via the gills and the urine. The general responses of C.kraussi to dilutions of sea water are discussed. Various suggestions for conservation measures based on the distribution and iife cycle of C.kraussi were made. The factors affecting the distribution of C.kraussi are discussed. The problem of the larval development in C.kraussi was discussed in relation to reviews of larval types of benthic invertebrates. The importance of the burrow, the possible route by which C.kraussi has invaded estuaries and the differences between open and closed estuaries as shown by the effects on C.kraussi were discussed.
- Full Text:
- Date Issued: 1974
- Authors: Forbes, Anthony Tonks
- Date: 1974
- Subjects: Estuarine biology -- South Africa Shrimps -- South Africa Decapoda (Crustacea) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5850 , http://hdl.handle.net/10962/d1011866
- Description: The distribution of Callianassa kraussi in southern Africa extends from Lamberts Bay on the west coast to San Martinho in Mocambique. This represents a northerly extension of the range from the previous known limit of Inhaca Island. In this area 59 localities were visited and records obtained for an additional 16. Three areas were selected for detailed study. These were the west Kleinemonde estuary, which is normally closed off from the sea by a sand bar and the open Swartkops estuary both on the southeastern Cape coast, and the Swartvlei system, which consists of a lake connected to the sea by a channel which closes intermittently, on the southern Cape coast. The nature of the burrows constructed by C. kraussi was investigated in these areas. Burrow complexes may have up to nine entrances but more commonly two to four. Laboratory studies suggest that the number of entrances does not exceed the number of prawns present and consequently burrow opening counts will give an estimate of population density. Water movement can result in the closing off of burrows while strong water and sand movement will exclude C.kraussi from an area. C.kraussi is also excluded from areas which have very coarse substrates. A three year regular sampling program showed that C.kraussi breeds mainly in winter/spring with a smaller breeding peak in summer. Egg development time at 20°C in a salinity of 35° /₀₀ is 30-33 days. There are two larval stages which last 3-5 days. Development time of the eggs is tripled at temperatures of 13-15°C while larval development time is extended to 9-14 days. Development is possibly slightly accelerated at 25 ± 3°C but the number of eggs hatching is markedly reduced. Larval development times were similar to those at 20° and 35°/₀₀. There are no planktonic larval stages. Growth was more rapid and greater size was attained in the open Swartkops estuary than in the closed Kleinemonde estuary. Prawns hatching in winter/spring breed for the first time in the following summer at an age of about 16 months and then again in the following winter/spring at an age of about 2 years. Prawns hatching in summer breed in the following winter at an age of about 18 months and then again in the immediately following summer. Longevity in both sexes is about 2 years. Dispersal is accomplished by migration of the post-larval juvenile phases at an age of 3-5 months. Non-selfmaintaining populations exist in areas where salinities are too low to permit breeding. Population densities were found to vary markedly in different areas. Investigations of osmotic and ionic regulation showed that C.kraussi is a strong hyper-regulator and thus distinct from any other known species in the genus. Volume regulatory ability is well developed and depends on variable rates of urine production. Salt loss in dilutions occurs almost equally via the gills and the urine. The general responses of C.kraussi to dilutions of sea water are discussed. Various suggestions for conservation measures based on the distribution and iife cycle of C.kraussi were made. The factors affecting the distribution of C.kraussi are discussed. The problem of the larval development in C.kraussi was discussed in relation to reviews of larval types of benthic invertebrates. The importance of the burrow, the possible route by which C.kraussi has invaded estuaries and the differences between open and closed estuaries as shown by the effects on C.kraussi were discussed.
- Full Text:
- Date Issued: 1974
Genetic studies on collagenolytic achromobacter strains and their bacteriophages
- Authors: Thomson, Jennifer Ann
- Date: 1974
- Subjects: Bacteriophages -- Genetics Bacterial genetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4246 , http://hdl.handle.net/10962/d1007291
- Description: From Summary: A survey of collagenolytic aerobic bacteria from cured hides yielded three strains of Bacillus and eight of Achromobacter which degraded collagen at 0.4 M NaCl. Achromobacter sp. 2 was chosen for genetic studies due to its high collagenolytic activity and the lack of genetic information on Achromobacter. Four temperate bacteriophages specific for Achromobacter sp. 2 were isolated and their relationships studied. The phages caused lysogenic conversion resulting in the inability of lysogens to adsorb phage. Achromobacter sp. 2 was shown to be a cryptic lysogen as it was not immune to superinfection but had a very low rate of spontaneous induction which could be increased with mutagens. It is proposed that the cryptic lysogeny of this strain is maintained by a defective excision mechanism and the mode of prophage integration in the host chromosome. DNA extracted from phage α3a was used to transfect spheroplasts. The optimal conditions for the development of competence for transfection were determined. The presence of nuclease-attack on phage DNA under conditions of prolonged incubation of DNA and spheroplasts was proposed. A method for extracting Achromobacter DNA was devised which yielded purified, undegraded DNA, but it was not possible to transform Achromobacter sp. 2 with this DNA. The a phages were used to transduce a number of genetic markers into Achromobacter auxotrophs. The transduct ants had the ability to release the cryptic α3 prophage at a high rate while maintaining their sensitivity to homologous phage infection. It is proposed that this is due to complementation between the cryptic prophage and the residual phage functions in the transducing particles. The transductants segregated auxotrophs with a probability of 10⁻³ per cell per generation. It appears that an unusual system of generalised transduction is operating whereby the transducing particles contain both phage and bacterial DNA which is incorporated into the recipient genome by a single recombination event yielding unstable transductants. In a study on induction of Escherichia coli (λ), carcinogenic nitrosamines were shown to be inducers of phage development. This provides a screening system for potentially harmful nitrosamines.
- Full Text:
- Date Issued: 1974
- Authors: Thomson, Jennifer Ann
- Date: 1974
- Subjects: Bacteriophages -- Genetics Bacterial genetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4246 , http://hdl.handle.net/10962/d1007291
- Description: From Summary: A survey of collagenolytic aerobic bacteria from cured hides yielded three strains of Bacillus and eight of Achromobacter which degraded collagen at 0.4 M NaCl. Achromobacter sp. 2 was chosen for genetic studies due to its high collagenolytic activity and the lack of genetic information on Achromobacter. Four temperate bacteriophages specific for Achromobacter sp. 2 were isolated and their relationships studied. The phages caused lysogenic conversion resulting in the inability of lysogens to adsorb phage. Achromobacter sp. 2 was shown to be a cryptic lysogen as it was not immune to superinfection but had a very low rate of spontaneous induction which could be increased with mutagens. It is proposed that the cryptic lysogeny of this strain is maintained by a defective excision mechanism and the mode of prophage integration in the host chromosome. DNA extracted from phage α3a was used to transfect spheroplasts. The optimal conditions for the development of competence for transfection were determined. The presence of nuclease-attack on phage DNA under conditions of prolonged incubation of DNA and spheroplasts was proposed. A method for extracting Achromobacter DNA was devised which yielded purified, undegraded DNA, but it was not possible to transform Achromobacter sp. 2 with this DNA. The a phages were used to transduce a number of genetic markers into Achromobacter auxotrophs. The transduct ants had the ability to release the cryptic α3 prophage at a high rate while maintaining their sensitivity to homologous phage infection. It is proposed that this is due to complementation between the cryptic prophage and the residual phage functions in the transducing particles. The transductants segregated auxotrophs with a probability of 10⁻³ per cell per generation. It appears that an unusual system of generalised transduction is operating whereby the transducing particles contain both phage and bacterial DNA which is incorporated into the recipient genome by a single recombination event yielding unstable transductants. In a study on induction of Escherichia coli (λ), carcinogenic nitrosamines were shown to be inducers of phage development. This provides a screening system for potentially harmful nitrosamines.
- Full Text:
- Date Issued: 1974
Social criteria in the drama of Molìère
- Authors: Brooks, Beverley Anne
- Date: 1974
- Subjects: Molière, 1622-1673 -- Criticism and interpretation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3627 , http://hdl.handle.net/10962/d1009758
- Description: It is by no means an easy task to analyse and interpret the work of a dramatist such as Molière, for an interval of three hundred years inevitably blurs our perspective of the man and his intentions. We find ourselves unconsciously reading more into his lines than he possibly meant us to. We are tempted to attach significance to certain words and disregard others, in an arbitrary fashion. We try to reconstruct Molière's attitude towards his contemporaries and theirs to him, from evidence that is often flimsy and seldom reliable. Molière's very identity has been questioned to the extent that the authorship of his plays has been variously attributed to such different personalities as Louis XIV and the great Corneilleo. To these problems is added a further complication when one embarks upon a thesis dealing with the picture of society as it emerges from Molière's plays. Not only are we confronted with the difficulty of interpretation already mentioned, but also with the vastly different way in which pre-enlightenment man regarded social and political institutions. We of the twentieth century tend to take for granted the notions of liberty, fraternity, and equality. Had anyone formulated such ideas in the seventeenth century, it is doubtful whether they would have been accepted, since they contradict the very concept upon which society was based in the age of Louis XIV. This concept, broadly speaking, is that of a strict hierarchy in which everyone has his own appointed place. Obviously the notion of a hierarchy pre-supposes the inferiority of some and the superiority of others in the social structure of the day; and post-enlightenment thinking does not readily accept that some men should be privileged and others regarded as belonging naturally to the lower orders. Intro., p. 1-2.
- Full Text:
- Date Issued: 1974
- Authors: Brooks, Beverley Anne
- Date: 1974
- Subjects: Molière, 1622-1673 -- Criticism and interpretation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3627 , http://hdl.handle.net/10962/d1009758
- Description: It is by no means an easy task to analyse and interpret the work of a dramatist such as Molière, for an interval of three hundred years inevitably blurs our perspective of the man and his intentions. We find ourselves unconsciously reading more into his lines than he possibly meant us to. We are tempted to attach significance to certain words and disregard others, in an arbitrary fashion. We try to reconstruct Molière's attitude towards his contemporaries and theirs to him, from evidence that is often flimsy and seldom reliable. Molière's very identity has been questioned to the extent that the authorship of his plays has been variously attributed to such different personalities as Louis XIV and the great Corneilleo. To these problems is added a further complication when one embarks upon a thesis dealing with the picture of society as it emerges from Molière's plays. Not only are we confronted with the difficulty of interpretation already mentioned, but also with the vastly different way in which pre-enlightenment man regarded social and political institutions. We of the twentieth century tend to take for granted the notions of liberty, fraternity, and equality. Had anyone formulated such ideas in the seventeenth century, it is doubtful whether they would have been accepted, since they contradict the very concept upon which society was based in the age of Louis XIV. This concept, broadly speaking, is that of a strict hierarchy in which everyone has his own appointed place. Obviously the notion of a hierarchy pre-supposes the inferiority of some and the superiority of others in the social structure of the day; and post-enlightenment thinking does not readily accept that some men should be privileged and others regarded as belonging naturally to the lower orders. Intro., p. 1-2.
- Full Text:
- Date Issued: 1974
Some adaptations of myrmeleontid (Neuroptera) and rhagionid (Diptera) larvae to life in hot dry sand
- Authors: Youthed, Gayle Jean
- Date: 1974
- Subjects: Ant lions Rhagionidae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5818 , http://hdl.handle.net/10962/d1007228
- Description: From Introduction: Larvae of the families Myrmeleontidae, Neuroptera, (ant-lions) and Rhagionidae, Diptera, (worm-lions) all live in hot dry sand. Many of the ant-lion larvae and all the worm-lion larvae, construct small conical pits in the sand which are used for the capture of prey (Haub, 1942; Youthed and Horan, 1969a). Those ant-lion larvae which do not construct pits lie in wait for their prey just below the surface of the sand.
- Full Text:
- Date Issued: 1974
Some adaptations of myrmeleontid (Neuroptera) and rhagionid (Diptera) larvae to life in hot dry sand
- Authors: Youthed, Gayle Jean
- Date: 1974
- Subjects: Ant lions Rhagionidae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5818 , http://hdl.handle.net/10962/d1007228
- Description: From Introduction: Larvae of the families Myrmeleontidae, Neuroptera, (ant-lions) and Rhagionidae, Diptera, (worm-lions) all live in hot dry sand. Many of the ant-lion larvae and all the worm-lion larvae, construct small conical pits in the sand which are used for the capture of prey (Haub, 1942; Youthed and Horan, 1969a). Those ant-lion larvae which do not construct pits lie in wait for their prey just below the surface of the sand.
- Full Text:
- Date Issued: 1974
The council of advice at the Cape of Good Hope, 1825-1834: a study in colonial government
- Authors: Donaldson, Margaret E
- Date: 1974
- Subjects: South Africa -- History -- To 1836 Great Britain -- Colonies -- Administration Cape of Good Hope (South Africa) -- History -- 1795-1872
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2603 , http://hdl.handle.net/10962/d1011220
- Description: The Council of Advice first emerged as a constitutional device for colonial rule in colonies captured by Britain during the wars against France between 1793 and 1814. The search for some new form of government for colonies of conquest had been necessitated by the difficulty generally experienced in assimilating formerly foreign colonies into the traditional British pattern of representation. Experience in Quebec between 1764 and 1791 had led to the gradual recognition of conciliar government as a workable substitute to bridge the gap between military rule and the grant of representative institutions. Between 1794 when a Council of Advice was first introduced in the island of San Domingo, and 1825, when the Cape of Good Hope was granted a council of this type, the composition, function and scope of such councils was gradually defined and elaborated. There was a continual interplay of precedent and example from one colony to another, facilitated by the growth of the Colonial Office in London during the early decades of the 19th Century. Councils of Advice were also introduced into some a-typical colonies of settlement, notably New South Wales, where the particular circumstances of the colony gave rise to the further development of the conciliar pattern of government, influenced by the practical experience in Quebec prior to 1791. Thus the Council of Advice at the Cape of Good Hope from 1825-1834 was but one example of an instrument of government which was being widely used in the British empire, and which was still developing in form and function during the period under consideration. The Council of Advice at the Cape reflects this fluidity. The composition of the council was altered on several occasions during the nine years of its existence; the degree of independence allowed to council members was a question which arose on several occasions, especially in relation to discussion of policy decisions taken in London; moreover, the council met at the discretion of the governor and four different men held this office during the period 1825-34, each with his own individual idea of the function and value of a council of advice. Preface, p. 1-2.
- Full Text:
- Date Issued: 1974
- Authors: Donaldson, Margaret E
- Date: 1974
- Subjects: South Africa -- History -- To 1836 Great Britain -- Colonies -- Administration Cape of Good Hope (South Africa) -- History -- 1795-1872
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2603 , http://hdl.handle.net/10962/d1011220
- Description: The Council of Advice first emerged as a constitutional device for colonial rule in colonies captured by Britain during the wars against France between 1793 and 1814. The search for some new form of government for colonies of conquest had been necessitated by the difficulty generally experienced in assimilating formerly foreign colonies into the traditional British pattern of representation. Experience in Quebec between 1764 and 1791 had led to the gradual recognition of conciliar government as a workable substitute to bridge the gap between military rule and the grant of representative institutions. Between 1794 when a Council of Advice was first introduced in the island of San Domingo, and 1825, when the Cape of Good Hope was granted a council of this type, the composition, function and scope of such councils was gradually defined and elaborated. There was a continual interplay of precedent and example from one colony to another, facilitated by the growth of the Colonial Office in London during the early decades of the 19th Century. Councils of Advice were also introduced into some a-typical colonies of settlement, notably New South Wales, where the particular circumstances of the colony gave rise to the further development of the conciliar pattern of government, influenced by the practical experience in Quebec prior to 1791. Thus the Council of Advice at the Cape of Good Hope from 1825-1834 was but one example of an instrument of government which was being widely used in the British empire, and which was still developing in form and function during the period under consideration. The Council of Advice at the Cape reflects this fluidity. The composition of the council was altered on several occasions during the nine years of its existence; the degree of independence allowed to council members was a question which arose on several occasions, especially in relation to discussion of policy decisions taken in London; moreover, the council met at the discretion of the governor and four different men held this office during the period 1825-34, each with his own individual idea of the function and value of a council of advice. Preface, p. 1-2.
- Full Text:
- Date Issued: 1974
The ecology of juvenile Rhabdosargus holubi (Steinachner) (Teleostei : Sparidae)
- Authors: Blaber, Stephen J M
- Date: 1974
- Subjects: Osteichthyes Fishes -- Breeding Fish populations Fish culture -- South Africa Estuaries -- South Africa -- Eastern Cape Aquatic ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5672 , http://hdl.handle.net/10962/d1005357
- Description: INTRODUCTION: Estuaries have received considerable attention from biologists in southern Africa in the past thirty years. Professor J.H. Day and the Zoology Department of the University of Cape Town have undertaken ecological surveys of a large number of estuaries of a variety of types, laying the important groundwork for more detailed studies of single species or problems. Their studies showed that the fish populations of southern African estuaries consist mainly of marine species. Why and when these species enter or leave the estuaries and whether they grow or breed in them were not established. The only relatively detailed study of a fish in southern African estuaries was that of Talbot (1955) who investigated aspects of the growth, feeding and reproduction of Rhabdosargus globiceps (Cuvier). No quantitative information has been published on any of the fish species, perhaps due to the difficulty of obtaining such data; results such as population estimates, mortality rates and growth rates are particularly unreliable when the area being investigated is in direct contact with the sea. Studies relating to even a single species of fish are hampered by immigration and emigration between estuary and sea, which make the population continuously variable. The larger estuaries are also difficult to sample adequately, especially with regard to netting, except perhaps on a very large scale using expensive commercial equipment. Along the southern African coast many of the smaller estuaries with a limited catchment area are cut off from the sea for most of the year due to erratic rainfall and longshore drift of sand. These closed or 'blind' estuaries of south eastern Africa, of which there are at least thirty in the eastern Cape Province, provide excellent areas for studying estuarine fish populations which enter when the estuary is open to the sea, but become isolated once it closes. These fish which become cut off in closed estuaries are subject to a new series of conditions. They are exposed to the wider temperature and salinity fluctuations of an estuary and they are forced to utilise the food resources of the estuary. Additionally they may be subjected to predation from piscivorous birds, and those predatory fish which are also cut off in the estuary. These factors will affect the size, mortality, and growth rates of a fish population. Since the fish are isolated no recruitment from the sea can take place, and any increase in numbers would have to come from breeding within the estuary. It is inevitable that the most numerous species should receive attention first. Rhabdosargus holubi (Steindachner) (Synonomy : Sargus holubi Stndr, Austrosparus tricuspidens Smith, Rhabdosargus tricuspidens (Smith))(Plate 1) is one of the most abundant fish in the estuaries of the eastern Cape Province. According to Smith (1965) it is endemic to southern Africa, occurring from the Cape to Zululand, being most common between Mossel Bay and East London. It is largely replaced by Rhabdosargus sarba (Forskal) in the north of its range and by Rhabdosargus globiceps (Cuvier) in the south. Commonly called the 'flatty' or silver bream it is considered only as being of nuisance value by fishermen, seldom exceeding 30 cm in length. In this study the ecology of R.holubi was examined in relation to the closed West Kleinemond estuary which is a small 'blind' estuary typical of those found along the eastern Cape coast. The growth, mortality and population size of R.holubi in this estuary were investigated and linked where possible with predation and detailed studies into the tolerances, food, and feeding of the species. It was not known at the commencement of the study whether breeding could occur in estuaries, although Smith (1965) stated that R.holubi does breed in estuaries. During the course of the sampling programme in the West Kleinemond estuary, measurements of the growth and population structure of two other species of fish were recorded for comparison with R.holubi: the sparid Lithognathus lithognathus (Cuvier) (White Steenbras) and the piscivorous carangid Hypacanthas amia (L.) (Leervis or garrick). Laboratory studies on R.holubi were possible due to the fact that large numbers of this species could be caught in eastern Cape estuaries and transported to Grahamstown, where they could be maintained in captivity for up to four months in recirculating seawater aquaria. During the course of the study over 2000 fish were kept in captivity at different times for a variety of experiments. Another 2500 were preserved for gut analyses and lipid determinations, while over 5000 were captured, examined and released in the field.
- Full Text:
- Date Issued: 1974
- Authors: Blaber, Stephen J M
- Date: 1974
- Subjects: Osteichthyes Fishes -- Breeding Fish populations Fish culture -- South Africa Estuaries -- South Africa -- Eastern Cape Aquatic ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5672 , http://hdl.handle.net/10962/d1005357
- Description: INTRODUCTION: Estuaries have received considerable attention from biologists in southern Africa in the past thirty years. Professor J.H. Day and the Zoology Department of the University of Cape Town have undertaken ecological surveys of a large number of estuaries of a variety of types, laying the important groundwork for more detailed studies of single species or problems. Their studies showed that the fish populations of southern African estuaries consist mainly of marine species. Why and when these species enter or leave the estuaries and whether they grow or breed in them were not established. The only relatively detailed study of a fish in southern African estuaries was that of Talbot (1955) who investigated aspects of the growth, feeding and reproduction of Rhabdosargus globiceps (Cuvier). No quantitative information has been published on any of the fish species, perhaps due to the difficulty of obtaining such data; results such as population estimates, mortality rates and growth rates are particularly unreliable when the area being investigated is in direct contact with the sea. Studies relating to even a single species of fish are hampered by immigration and emigration between estuary and sea, which make the population continuously variable. The larger estuaries are also difficult to sample adequately, especially with regard to netting, except perhaps on a very large scale using expensive commercial equipment. Along the southern African coast many of the smaller estuaries with a limited catchment area are cut off from the sea for most of the year due to erratic rainfall and longshore drift of sand. These closed or 'blind' estuaries of south eastern Africa, of which there are at least thirty in the eastern Cape Province, provide excellent areas for studying estuarine fish populations which enter when the estuary is open to the sea, but become isolated once it closes. These fish which become cut off in closed estuaries are subject to a new series of conditions. They are exposed to the wider temperature and salinity fluctuations of an estuary and they are forced to utilise the food resources of the estuary. Additionally they may be subjected to predation from piscivorous birds, and those predatory fish which are also cut off in the estuary. These factors will affect the size, mortality, and growth rates of a fish population. Since the fish are isolated no recruitment from the sea can take place, and any increase in numbers would have to come from breeding within the estuary. It is inevitable that the most numerous species should receive attention first. Rhabdosargus holubi (Steindachner) (Synonomy : Sargus holubi Stndr, Austrosparus tricuspidens Smith, Rhabdosargus tricuspidens (Smith))(Plate 1) is one of the most abundant fish in the estuaries of the eastern Cape Province. According to Smith (1965) it is endemic to southern Africa, occurring from the Cape to Zululand, being most common between Mossel Bay and East London. It is largely replaced by Rhabdosargus sarba (Forskal) in the north of its range and by Rhabdosargus globiceps (Cuvier) in the south. Commonly called the 'flatty' or silver bream it is considered only as being of nuisance value by fishermen, seldom exceeding 30 cm in length. In this study the ecology of R.holubi was examined in relation to the closed West Kleinemond estuary which is a small 'blind' estuary typical of those found along the eastern Cape coast. The growth, mortality and population size of R.holubi in this estuary were investigated and linked where possible with predation and detailed studies into the tolerances, food, and feeding of the species. It was not known at the commencement of the study whether breeding could occur in estuaries, although Smith (1965) stated that R.holubi does breed in estuaries. During the course of the sampling programme in the West Kleinemond estuary, measurements of the growth and population structure of two other species of fish were recorded for comparison with R.holubi: the sparid Lithognathus lithognathus (Cuvier) (White Steenbras) and the piscivorous carangid Hypacanthas amia (L.) (Leervis or garrick). Laboratory studies on R.holubi were possible due to the fact that large numbers of this species could be caught in eastern Cape estuaries and transported to Grahamstown, where they could be maintained in captivity for up to four months in recirculating seawater aquaria. During the course of the study over 2000 fish were kept in captivity at different times for a variety of experiments. Another 2500 were preserved for gut analyses and lipid determinations, while over 5000 were captured, examined and released in the field.
- Full Text:
- Date Issued: 1974
"The isolation and estimation of low molecular weight N-nitrosamines in biological materials"
- Authors: Du Plessis, Leo Stephen
- Date: 1973
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21176 , http://hdl.handle.net/10962/6750
- Description: Summary: Low molecular weight N-nitrosamines were detected by ultraviolet, infrared, nuclear magnetic resonance, mass spectral, thin-layer chromatographic and gas liquid chromatographic means. A method for the estimation of dimethylnitrosamine, diethylnitrosamine, ethal-n-propylnitrosamine and di-n-propylnitrosamine has been developed. The method involves the isolation of the nitrosamines in an aqueous distillate by freeze-drying. After extraction of the nitrosamines from the aqueous distillate by means of dichloromethane, their separation and quantitative estimation are achieved by gas liquid chromatography of the extract. The procedure can be extended down to the ppb range. Dimethylnitrosamine was isolated from an extract of Solanum incanum and identified by gas liquid chromatography on four different columns, infrared and nuclear magnetic resonance spectroscopy.
- Full Text:
- Date Issued: 1973
- Authors: Du Plessis, Leo Stephen
- Date: 1973
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21176 , http://hdl.handle.net/10962/6750
- Description: Summary: Low molecular weight N-nitrosamines were detected by ultraviolet, infrared, nuclear magnetic resonance, mass spectral, thin-layer chromatographic and gas liquid chromatographic means. A method for the estimation of dimethylnitrosamine, diethylnitrosamine, ethal-n-propylnitrosamine and di-n-propylnitrosamine has been developed. The method involves the isolation of the nitrosamines in an aqueous distillate by freeze-drying. After extraction of the nitrosamines from the aqueous distillate by means of dichloromethane, their separation and quantitative estimation are achieved by gas liquid chromatography of the extract. The procedure can be extended down to the ppb range. Dimethylnitrosamine was isolated from an extract of Solanum incanum and identified by gas liquid chromatography on four different columns, infrared and nuclear magnetic resonance spectroscopy.
- Full Text:
- Date Issued: 1973
A physico-chemical investigation of refractory hard metals
- Authors: Philip, Hamish Ian
- Date: 1973
- Subjects: Refractory materials Heat resistant alloys
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4441 , http://hdl.handle.net/10962/d1007630
- Description: In this investigation, the resistivity of vanadium nitride at elevated temperatures has been measured using a resistance bridge based on the Dauphinée/Mooser (1955) chopper system. In general, an almost linear increase of resistivity with temperature was observed for VN, but at certain temperatures, deviations from linearity (anomalies) were observed, these have been classified into three types. Attempts have been made to correlate the anomalous behaviour and temperature coefficients of resistivity with the ambient atmospheres and with the impurities, (especially oxygen), stoichiotmetry and density of this material. Oxygen and excess nitrogen appear to be electron donors in their effects on VN and result in a decrease in the slope of resistivity vs temperature curves. Oxygen and excess nitrogen also appear to increase the overall resistivity due to an increase in defect concentration. No effects due to the ambient atmosphere have been observed in the case of hot-pressed samples. lndicating that reaction can only occur if the reacting gases can reach the interior of the samples.
- Full Text:
- Date Issued: 1973
- Authors: Philip, Hamish Ian
- Date: 1973
- Subjects: Refractory materials Heat resistant alloys
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4441 , http://hdl.handle.net/10962/d1007630
- Description: In this investigation, the resistivity of vanadium nitride at elevated temperatures has been measured using a resistance bridge based on the Dauphinée/Mooser (1955) chopper system. In general, an almost linear increase of resistivity with temperature was observed for VN, but at certain temperatures, deviations from linearity (anomalies) were observed, these have been classified into three types. Attempts have been made to correlate the anomalous behaviour and temperature coefficients of resistivity with the ambient atmospheres and with the impurities, (especially oxygen), stoichiotmetry and density of this material. Oxygen and excess nitrogen appear to be electron donors in their effects on VN and result in a decrease in the slope of resistivity vs temperature curves. Oxygen and excess nitrogen also appear to increase the overall resistivity due to an increase in defect concentration. No effects due to the ambient atmosphere have been observed in the case of hot-pressed samples. lndicating that reaction can only occur if the reacting gases can reach the interior of the samples.
- Full Text:
- Date Issued: 1973
A structural investigation of the sulphated polysaccharide from Aeodes ulvoidea Schmitz
- Allsobrook, Anthony John Robert
- Authors: Allsobrook, Anthony John Robert
- Date: 1973
- Subjects: Red algae -- Composition Polysaccharides
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4437 , http://hdl.handle.net/10962/d1007482
- Description: Aeodes ulvoidea, a red seaweed of the Grateloupiaceae, yielded a highly sulphated polysaccharide which was shown to contain D- and L-galactose, 4-0-methy-L-galactose, 2-0-methyl - D- and L-galactose and 6-0-methyl-D-galactose, together with chromatographic traces of xylose and mannose. The sulphate was not labile to alkali, but it was largely removed with methanolic hydrogen chloride. Periodate oxidation of the polysaccharide, methylation of the de sulphated polysaccharide, and investigation of fifteen oligosaccharides from partial hydrolysis and acetolysis studies of the polysaccharide, indicate that (a) the polysaccharide is composed of a backbone of D-galactose residues which are 1,3- and 1,4-linked (b) at least some regions of alternating structure do occur (c) the 2-0-methylgalactose is linked through the 4-position (d) the 4-0-methyl-L-galactose is present as single unit side chains glycosidically linked to the galactose backbone at position 6, and (e) most of the 6-0-methyl-D-galactose is linked to the 4-position of 2-0-methyl-D-galactose.
- Full Text:
- Date Issued: 1973
- Authors: Allsobrook, Anthony John Robert
- Date: 1973
- Subjects: Red algae -- Composition Polysaccharides
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4437 , http://hdl.handle.net/10962/d1007482
- Description: Aeodes ulvoidea, a red seaweed of the Grateloupiaceae, yielded a highly sulphated polysaccharide which was shown to contain D- and L-galactose, 4-0-methy-L-galactose, 2-0-methyl - D- and L-galactose and 6-0-methyl-D-galactose, together with chromatographic traces of xylose and mannose. The sulphate was not labile to alkali, but it was largely removed with methanolic hydrogen chloride. Periodate oxidation of the polysaccharide, methylation of the de sulphated polysaccharide, and investigation of fifteen oligosaccharides from partial hydrolysis and acetolysis studies of the polysaccharide, indicate that (a) the polysaccharide is composed of a backbone of D-galactose residues which are 1,3- and 1,4-linked (b) at least some regions of alternating structure do occur (c) the 2-0-methylgalactose is linked through the 4-position (d) the 4-0-methyl-L-galactose is present as single unit side chains glycosidically linked to the galactose backbone at position 6, and (e) most of the 6-0-methyl-D-galactose is linked to the 4-position of 2-0-methyl-D-galactose.
- Full Text:
- Date Issued: 1973
A study of Jewish identification and commitment in Johannesburg
- Authors: Dubb, Allie A
- Date: 1973
- Subjects: Jews -- South Africa -- Johannesburg Johannesburg (South Africa) -- Social conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3362 , http://hdl.handle.net/10962/d1011564
- Description: The present study is an investigation of the nature and extent of Jewish identification and commitment in the Johannesburg Jewish Community. Jewish identification is defined as the attitudes and behaviour through which Jews express their identity with each other and with the Jewish group. It is conceived as comprising several dimensions - structural, cultural, religious, etc . - each of which may be assessed in terms of attitudes and/or behaviour. The aim of the study is, in the first place to describe the various dimensions of Jewish identification and to discover relations between them, and between them and other variables. Fieldwork consisted in the administration of a schedule, lasting about an hour, by trained interviewers to a quota sample of Johannesburg Jews. The schedule comprised questions relating to behaviour, attitudes and personal particulars. These data were augmented by several intensive interviews and by interviewers' observations. The final sample consisted of 286 men and women, in almost equal proportions, who had answered affirmatively the initial question, "Are you Jewish?" Five hypotheses were postulated, mainly on the basis of the findings of several previous studies in the United States. Briefly, it was postulated: firstly, that Jews would tend to identify through their attitudes to a greater extent than through actual behaviour; secondly that the area in which identification on the behavioural level was most likely to be manifested, was in patterns of social relations; thirdly, that observance of religious rituals was primarily a manifestation of identification rather than religious commitment ; fourthly; that there was some conflict between the desire to maintain the group and the feeling that barriers between ethnic groups should be minimal; and, finally , that the boundaries of the .Jewish community could be defined most adequately in terms of the relevance to community membership to the allocation of roles rather than in cultural terms. The first hypothesis had to be partially rejected; the remaining four were confirmed by the data. The study comprises eleven Chapters: in the first four, the problem is defined, hypotheses stated and research and sampling methods discussed; in Chapter Five, the demographic background is described, and in Chapters Six to Ten the findings relating to the various dimensions are presented and the hypotheses tested. In the final Chapter, the hypotheses and various specific findings are discussed in relation to their wider theoretical implications, as well as to their possibilities for further research and practical applications.
- Full Text:
- Date Issued: 1973
- Authors: Dubb, Allie A
- Date: 1973
- Subjects: Jews -- South Africa -- Johannesburg Johannesburg (South Africa) -- Social conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3362 , http://hdl.handle.net/10962/d1011564
- Description: The present study is an investigation of the nature and extent of Jewish identification and commitment in the Johannesburg Jewish Community. Jewish identification is defined as the attitudes and behaviour through which Jews express their identity with each other and with the Jewish group. It is conceived as comprising several dimensions - structural, cultural, religious, etc . - each of which may be assessed in terms of attitudes and/or behaviour. The aim of the study is, in the first place to describe the various dimensions of Jewish identification and to discover relations between them, and between them and other variables. Fieldwork consisted in the administration of a schedule, lasting about an hour, by trained interviewers to a quota sample of Johannesburg Jews. The schedule comprised questions relating to behaviour, attitudes and personal particulars. These data were augmented by several intensive interviews and by interviewers' observations. The final sample consisted of 286 men and women, in almost equal proportions, who had answered affirmatively the initial question, "Are you Jewish?" Five hypotheses were postulated, mainly on the basis of the findings of several previous studies in the United States. Briefly, it was postulated: firstly, that Jews would tend to identify through their attitudes to a greater extent than through actual behaviour; secondly that the area in which identification on the behavioural level was most likely to be manifested, was in patterns of social relations; thirdly, that observance of religious rituals was primarily a manifestation of identification rather than religious commitment ; fourthly; that there was some conflict between the desire to maintain the group and the feeling that barriers between ethnic groups should be minimal; and, finally , that the boundaries of the .Jewish community could be defined most adequately in terms of the relevance to community membership to the allocation of roles rather than in cultural terms. The first hypothesis had to be partially rejected; the remaining four were confirmed by the data. The study comprises eleven Chapters: in the first four, the problem is defined, hypotheses stated and research and sampling methods discussed; in Chapter Five, the demographic background is described, and in Chapters Six to Ten the findings relating to the various dimensions are presented and the hypotheses tested. In the final Chapter, the hypotheses and various specific findings are discussed in relation to their wider theoretical implications, as well as to their possibilities for further research and practical applications.
- Full Text:
- Date Issued: 1973
A study of the ecology, behaviour and systematics of Tockus Hornbills
- Authors: Kemp, Alan Charles
- Date: 1973
- Subjects: Birds -- South Africa -- Kruger National Park -- Identification Birds -- South Africa -- Kruger National Park -- Ecology Birds -- South Africa -- Kruger National Park -- Breeding Birds -- Birds -- South Africa -- Kruger National Park -- Nutrition Birds -- South Africa -- Kruger National Park -- Physiology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5861 , http://hdl.handle.net/10962/d1012634
- Description: During the last decades ecology and behaviour have become of major importance in African ornithology. Not only have more individual species been studied in detail, but behaviour and ecology have been used in a more general sense in regional works (Benson et al 1971} and in zoogeographical treatises (Moreau 1966, Hall and Moreau 1970). As part of a world- wide trend, behaviour and ecology have also become important in systematics and taxonomy eg. Hall's 1963 study of francolin, and Benson et al's 1971 erection of the bush shrike family Malaconotidae. This dissertation fits into this trend, beginning with a detailed study of the ecology and behaviour of three species of hornbill of the genus Tockus, and extending the observations in less detail to five other members of the genus. Combined with the literature, these observations allow an analysis of the systematics and evolution of the genus Tokus to be undertaken, as well as supplying descriptive information on Tokus biology. Intro. p. 1.
- Full Text:
- Date Issued: 1973
- Authors: Kemp, Alan Charles
- Date: 1973
- Subjects: Birds -- South Africa -- Kruger National Park -- Identification Birds -- South Africa -- Kruger National Park -- Ecology Birds -- South Africa -- Kruger National Park -- Breeding Birds -- Birds -- South Africa -- Kruger National Park -- Nutrition Birds -- South Africa -- Kruger National Park -- Physiology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5861 , http://hdl.handle.net/10962/d1012634
- Description: During the last decades ecology and behaviour have become of major importance in African ornithology. Not only have more individual species been studied in detail, but behaviour and ecology have been used in a more general sense in regional works (Benson et al 1971} and in zoogeographical treatises (Moreau 1966, Hall and Moreau 1970). As part of a world- wide trend, behaviour and ecology have also become important in systematics and taxonomy eg. Hall's 1963 study of francolin, and Benson et al's 1971 erection of the bush shrike family Malaconotidae. This dissertation fits into this trend, beginning with a detailed study of the ecology and behaviour of three species of hornbill of the genus Tockus, and extending the observations in less detail to five other members of the genus. Combined with the literature, these observations allow an analysis of the systematics and evolution of the genus Tokus to be undertaken, as well as supplying descriptive information on Tokus biology. Intro. p. 1.
- Full Text:
- Date Issued: 1973
Aspects of the biology of aestivation in Bulinus (Physopsis) africanus (Krauss) (Gastropoda, Pulmonata)
- Authors: Heeg, J. (Jan)
- Date: 1973
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21054 , http://hdl.handle.net/10962/6178
- Description: Aestivation, a period of dormancy during hot, dry conditions, is known to occur in both the Prosobranchia and the Pulmonata among freshwater Gastropoda. While there have been numerous accounts, mainly by field ecologists concerned with bilharziasis control, of the survival value of aestivation in the Gastropoda, little is known of its underlying physiological mechanisms. Results of investigations into the physiological basis of aestivation in the freshwater Prosobranchia, confined to the family Ampulariidae, have been conflicting, fundamental differences having been shown to exist between different species of the genus Pila . Only a single comprehensive study, that by von Brand and his coworkers on the planorbid snail Australorbis glabratus*, forms the basis of our knowledge of the aestivation process in the aquatic Pulmonata. In view of the conflicting results obtained in investigations on freshwater Prosobranchia, the general applicability of the findings for Australorbis glabratus to other freshwater Pulmonata was open to question. The present investigation on the planorbid snail Bulinus (Physopsis) afriaanus, a species known to be a successful aestivator, was prompted by the obvious need for a further comprehensive study on an aquatic pulmonate species . The results presented here show that aestivation in this species is a definite physiological state, characterised by a depression of the metabolic rate, which not only aids in husbanding the snails I metabolic resources. during the enforced starvation which must necessarily accompany aestivation, but also constitutes a form of resistance adaptation to the transient high temperatures which aestivating snails are bound to encounter. Loss of body water is shown to be important in initiating aestivation, but it is also the factor most likely to prove lethal during the course of aestivation. The results confirm and extend the earlier findings for Australorbis glabratus. The results are discussed in the context of our present knowledge of aestivation in other Gastropoda, both aquatic and terrestrial, and also in relation to other forms of resistance adaptation. As expected, the investigation raises more questions than it answers, thus directions for further research, arising out of the present findings, are suggested.
- Full Text:
- Date Issued: 1973
- Authors: Heeg, J. (Jan)
- Date: 1973
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21054 , http://hdl.handle.net/10962/6178
- Description: Aestivation, a period of dormancy during hot, dry conditions, is known to occur in both the Prosobranchia and the Pulmonata among freshwater Gastropoda. While there have been numerous accounts, mainly by field ecologists concerned with bilharziasis control, of the survival value of aestivation in the Gastropoda, little is known of its underlying physiological mechanisms. Results of investigations into the physiological basis of aestivation in the freshwater Prosobranchia, confined to the family Ampulariidae, have been conflicting, fundamental differences having been shown to exist between different species of the genus Pila . Only a single comprehensive study, that by von Brand and his coworkers on the planorbid snail Australorbis glabratus*, forms the basis of our knowledge of the aestivation process in the aquatic Pulmonata. In view of the conflicting results obtained in investigations on freshwater Prosobranchia, the general applicability of the findings for Australorbis glabratus to other freshwater Pulmonata was open to question. The present investigation on the planorbid snail Bulinus (Physopsis) afriaanus, a species known to be a successful aestivator, was prompted by the obvious need for a further comprehensive study on an aquatic pulmonate species . The results presented here show that aestivation in this species is a definite physiological state, characterised by a depression of the metabolic rate, which not only aids in husbanding the snails I metabolic resources. during the enforced starvation which must necessarily accompany aestivation, but also constitutes a form of resistance adaptation to the transient high temperatures which aestivating snails are bound to encounter. Loss of body water is shown to be important in initiating aestivation, but it is also the factor most likely to prove lethal during the course of aestivation. The results confirm and extend the earlier findings for Australorbis glabratus. The results are discussed in the context of our present knowledge of aestivation in other Gastropoda, both aquatic and terrestrial, and also in relation to other forms of resistance adaptation. As expected, the investigation raises more questions than it answers, thus directions for further research, arising out of the present findings, are suggested.
- Full Text:
- Date Issued: 1973
Aspects of the biology of Boophilus decoloratus (Koch, 1844) (Acarina : ixodidae)
- Londt, Jason G H (Jason Gilbert Hayden), 1943-
- Authors: Londt, Jason G H (Jason Gilbert Hayden), 1943-
- Date: 1973
- Subjects: Ixodidae -- Development Ticks -- Development Boophilus -- Development
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5817 , http://hdl.handle.net/10962/d1007202
- Description: 1. The external morphology of all stages in the life cycle of B. decoloratus is described with the aid of scanning electron micrographs. 2. The biological activities of B. decoloratus during its parasitic cycle are examined with special reference to the course of feeding of all stages, and to the influence of the pharate nymph and adult conditions in accelerating the completion of the cycle. 3. The pattern of dropping of replete females is considered in relation to their weight and their time of drop-off. 4. The adult male population structure is described. Two distinct weight groups are reported and the taxonomic significance of these is discussed. 5. The preoviposition period duration of B .decoloratus was studied under laboratory conditions and found to be temperature dependent and humidity independent. Female size, as implied by their engorged weights, influenced the duration of the oviposition period: ticks weighing less than 20 mg possessed longer preoviposition periods. 6. The preoviposition period of B.decoloratus females under fluctuating macroclimatic conditions was studied and found to be long in duration. The implications of this are discussed in relation to laboratory findings and the summer build-up of this species in nature. 7. The duration of the oviposition period of B. decoloratus and the number of eggs produced during this period were studied under laboratory and field conditions. Both these parameters were found to be temperature dependent and uninfluenced by humidity. The significance of a temperature dependent oviposition period is discussed. 8. The minimum amount of 'blood' required by female ticks for oviposition of eggs was found to be approximately 16 mg. under laboratory conditions. 9. The oviposition behaviour of B. decoloratus females has been described and the water relations of ovipositing and non-ovipositing females were examined and discussed . 10. The effects of handling female ticks during their oviposition period was studied and females which were handled were found to produce significantly fewer eggs. The significance of this is discussed. 11. During preliminary experiments on the incubation period of B. decoloratus it was found that the viability of eggs laid during the first half of the oviposlting period was greater than for eggs laid in the second half of the period. The critical temperature of the 'wax' coating of eggs was found to be 42⁰C while the critical humidity was approximately 70% R.H. (7,53 mmHg) at 26⁰C. The implications of these findings are discussed. 12. The development of eggs, traced throughout the incubation period by monitoring the build-up of guanine spectrophotometrically, was studied under different humidity conditions . Successful development was found to be dependent on the water content of the eggs at the time of laying. As eggs were also found to be unable to take up water vapour from the atmosphere this finding is important evidence to support the suggestion that the survival of the egg stage largely determines the spacial distribution of larvae in the field. 13. Results of work done at constant, alternating and naturally fluctuating temperatures and humidities demonstrated that the duration of the incubation period of B.decoloratus is temperature dependent and humidity independent. The significance of this is discussed in relation to the findings of previous workers and to the biology of the species. 14. Egg viability (percentage hatch) was found to be humidity dependent and temperature independent. The implications of these findings are discussed. 15. Some of the problems associated with the assessment of the effects of climatic conditions on ticks are discussed. Special reference has been made to the advocation of using saturation deficit instead of relative humidity as the parameter indicative of environmental humidity in any biological study involving fluctuating humidity conditions. 16. The problems associated with having three variables (e.g. temperature, saturation deficit and incubation period duration) are discussed and reasons given for why contour diagrams have been used in this investigation. 17. A model of the interactions between the main abiotic factors of the environment (temperature and humidity) and the biological parameters studied during the second part of this investigation is presented. 18. The effects of climatic conditions on the life cycle and distribution of B.decoloratus are discussed. Special reference has been made to the available evidence explaining the summer build-up in tick numbers known to occur in nature and the way in which the present findings have helped in an understanding of the spacial distribution of B.decoloratus in the field.
- Full Text:
- Date Issued: 1973
- Authors: Londt, Jason G H (Jason Gilbert Hayden), 1943-
- Date: 1973
- Subjects: Ixodidae -- Development Ticks -- Development Boophilus -- Development
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5817 , http://hdl.handle.net/10962/d1007202
- Description: 1. The external morphology of all stages in the life cycle of B. decoloratus is described with the aid of scanning electron micrographs. 2. The biological activities of B. decoloratus during its parasitic cycle are examined with special reference to the course of feeding of all stages, and to the influence of the pharate nymph and adult conditions in accelerating the completion of the cycle. 3. The pattern of dropping of replete females is considered in relation to their weight and their time of drop-off. 4. The adult male population structure is described. Two distinct weight groups are reported and the taxonomic significance of these is discussed. 5. The preoviposition period duration of B .decoloratus was studied under laboratory conditions and found to be temperature dependent and humidity independent. Female size, as implied by their engorged weights, influenced the duration of the oviposition period: ticks weighing less than 20 mg possessed longer preoviposition periods. 6. The preoviposition period of B.decoloratus females under fluctuating macroclimatic conditions was studied and found to be long in duration. The implications of this are discussed in relation to laboratory findings and the summer build-up of this species in nature. 7. The duration of the oviposition period of B. decoloratus and the number of eggs produced during this period were studied under laboratory and field conditions. Both these parameters were found to be temperature dependent and uninfluenced by humidity. The significance of a temperature dependent oviposition period is discussed. 8. The minimum amount of 'blood' required by female ticks for oviposition of eggs was found to be approximately 16 mg. under laboratory conditions. 9. The oviposition behaviour of B. decoloratus females has been described and the water relations of ovipositing and non-ovipositing females were examined and discussed . 10. The effects of handling female ticks during their oviposition period was studied and females which were handled were found to produce significantly fewer eggs. The significance of this is discussed. 11. During preliminary experiments on the incubation period of B. decoloratus it was found that the viability of eggs laid during the first half of the oviposlting period was greater than for eggs laid in the second half of the period. The critical temperature of the 'wax' coating of eggs was found to be 42⁰C while the critical humidity was approximately 70% R.H. (7,53 mmHg) at 26⁰C. The implications of these findings are discussed. 12. The development of eggs, traced throughout the incubation period by monitoring the build-up of guanine spectrophotometrically, was studied under different humidity conditions . Successful development was found to be dependent on the water content of the eggs at the time of laying. As eggs were also found to be unable to take up water vapour from the atmosphere this finding is important evidence to support the suggestion that the survival of the egg stage largely determines the spacial distribution of larvae in the field. 13. Results of work done at constant, alternating and naturally fluctuating temperatures and humidities demonstrated that the duration of the incubation period of B.decoloratus is temperature dependent and humidity independent. The significance of this is discussed in relation to the findings of previous workers and to the biology of the species. 14. Egg viability (percentage hatch) was found to be humidity dependent and temperature independent. The implications of these findings are discussed. 15. Some of the problems associated with the assessment of the effects of climatic conditions on ticks are discussed. Special reference has been made to the advocation of using saturation deficit instead of relative humidity as the parameter indicative of environmental humidity in any biological study involving fluctuating humidity conditions. 16. The problems associated with having three variables (e.g. temperature, saturation deficit and incubation period duration) are discussed and reasons given for why contour diagrams have been used in this investigation. 17. A model of the interactions between the main abiotic factors of the environment (temperature and humidity) and the biological parameters studied during the second part of this investigation is presented. 18. The effects of climatic conditions on the life cycle and distribution of B.decoloratus are discussed. Special reference has been made to the available evidence explaining the summer build-up in tick numbers known to occur in nature and the way in which the present findings have helped in an understanding of the spacial distribution of B.decoloratus in the field.
- Full Text:
- Date Issued: 1973
Critical studies of John Milton, T.S. Eliot and other writers
- Authors: Peter, John Desmond
- Date: 1973
- Subjects: Milton, John, 1608-1674 -- Paradise lost , Crashaw, Richard, 1613?-1649 -- Criticism and interpretation , Joyce, James, 1882-1941 -- Criticism and interpretation , Coleridge, Samuel Taylor, 1772-1834 -- Criticism and interpretation , Marston, John, 1575?-1634 -- Criticism and interpretation , Eliot, T. S. (Thomas Stearns), 1888-1965 -- Criticism and interpretation
- Language: English
- Type: Thesis , Doctoral , DLitt
- Identifier: vital:2329 , http://hdl.handle.net/10962/d1018265
- Full Text:
- Date Issued: 1973
- Authors: Peter, John Desmond
- Date: 1973
- Subjects: Milton, John, 1608-1674 -- Paradise lost , Crashaw, Richard, 1613?-1649 -- Criticism and interpretation , Joyce, James, 1882-1941 -- Criticism and interpretation , Coleridge, Samuel Taylor, 1772-1834 -- Criticism and interpretation , Marston, John, 1575?-1634 -- Criticism and interpretation , Eliot, T. S. (Thomas Stearns), 1888-1965 -- Criticism and interpretation
- Language: English
- Type: Thesis , Doctoral , DLitt
- Identifier: vital:2329 , http://hdl.handle.net/10962/d1018265
- Full Text:
- Date Issued: 1973
Metal complexes of black wattle tannins and related model polyphenols
- Authors: Slabbert, Neville Patrick
- Date: 1973
- Subjects: Metal complexes Tannins
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4432 , http://hdl.handle.net/10962/d1007407
- Description: Apart from their general usage as tanning agents for hides and skins, the natural tannins have been used since earliest times for various other purposes. The blue-black iron tannate complex was used by ancient Egyptians as a hairdye and for many conturies this complex was the main source of writing inks. Wattle tannin is known to form complexes with many metal ions. The chief use of tannin complexes has been in gravimetric analyses, since aqueous solutions of tannins readily precipitate metal ions under certain experimentel conditions. At the present time the nature of the precipitated complexes has not been investigated however, because in the gravimetric method the complexes are ignited and the metal determined as its oxide; hence no knowledge of the complexes themselves was required.
- Full Text:
- Date Issued: 1973
- Authors: Slabbert, Neville Patrick
- Date: 1973
- Subjects: Metal complexes Tannins
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4432 , http://hdl.handle.net/10962/d1007407
- Description: Apart from their general usage as tanning agents for hides and skins, the natural tannins have been used since earliest times for various other purposes. The blue-black iron tannate complex was used by ancient Egyptians as a hairdye and for many conturies this complex was the main source of writing inks. Wattle tannin is known to form complexes with many metal ions. The chief use of tannin complexes has been in gravimetric analyses, since aqueous solutions of tannins readily precipitate metal ions under certain experimentel conditions. At the present time the nature of the precipitated complexes has not been investigated however, because in the gravimetric method the complexes are ignited and the metal determined as its oxide; hence no knowledge of the complexes themselves was required.
- Full Text:
- Date Issued: 1973
Studies in the South African Bulbous liliaceae
- Authors: Jessop, John Peter
- Date: 1973
- Subjects: Bulbs (Plants) -- South Africa Liliaceae -- South Africa Lilies -- South Africa Liliaceae -- Classification -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4261 , http://hdl.handle.net/10962/d1012563
- Description: The work comprises two principal sections; an attempt at ellucidating generic relationships in the South African bulbous Liliaceae, and a revision of the species of selected genera. In the first section the approaches investigated were: 1) A re-evaluation of the nature of the bulb apex, showing a likelihood that certain groups possess axillary and other groups terminal inflorescences. 2) An investigation of leaf anatomy, showing that most genera have very similar leaf structure, but that a few genera do differ from this norm. Scilla (Euscilla) generally possesses a distinctly lignified bundle sheath and the Urginea-Drimia group show a great range in structures - including a palisade. 3) An impression technique to determine patterns in the surface of the leaf cuticle. A close correlation appears to exist between these patterns and leaf shape. 4) Scanning Electron Microscope pictures of pollen revealed a considerable uniformity within the group and between this group and most other members of the Liliaceae. 5) Scanning Electron Microscope pictures of seeds revealed two main groups in the bulbous Liliaceae determined on the appearance of the cell walls of the testa. 6) A simple chromatographic technique was not found to be useful. 7) An investigation of chromosome numbers of. 44 samples of 15 species supplemented published data in allowing an analysis to be made of the application of chromosome numbers to generic concepts. Many genera of the Liliaceae - especially in the bulbous group - have extremely variable chromosome numbers. It is considered that numbers are more applicable to tribal than to generic concepts. Few indications of meiotic abnormalities were detected. Phylogenetic and taxonomic aspects of the genera of the bulbous Liliaceae are discussed and a key to the South African bulbous Liliaceae genera constructed. The following generic alterations are proposed: Ledebouria to be split off Scilla. Schizocarphus to be placed in Scilla. Resnova to be placed in Drimiopsis. The Astemme section (= Neobakeria) to be removed from Polyxena and placed in Massonia. The Cape species of Hyacinthus to be placed in Polyxena. Thuranthos, Urgineopsis and Urginea to be placed in Drimia. It is suggested that Schizobasis and Bowiea are of great importance in explaining the origin of Asparagus - possibly even directly from this group. In the generic revisions, thirteen genera are dealt with including typification, synonymy, distribution, field notes, species descriptions and keys. 67 species are dealt with, of which three are new (all in Ledebouria), and 31 new combinations are proposed.
- Full Text:
- Date Issued: 1973
- Authors: Jessop, John Peter
- Date: 1973
- Subjects: Bulbs (Plants) -- South Africa Liliaceae -- South Africa Lilies -- South Africa Liliaceae -- Classification -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4261 , http://hdl.handle.net/10962/d1012563
- Description: The work comprises two principal sections; an attempt at ellucidating generic relationships in the South African bulbous Liliaceae, and a revision of the species of selected genera. In the first section the approaches investigated were: 1) A re-evaluation of the nature of the bulb apex, showing a likelihood that certain groups possess axillary and other groups terminal inflorescences. 2) An investigation of leaf anatomy, showing that most genera have very similar leaf structure, but that a few genera do differ from this norm. Scilla (Euscilla) generally possesses a distinctly lignified bundle sheath and the Urginea-Drimia group show a great range in structures - including a palisade. 3) An impression technique to determine patterns in the surface of the leaf cuticle. A close correlation appears to exist between these patterns and leaf shape. 4) Scanning Electron Microscope pictures of pollen revealed a considerable uniformity within the group and between this group and most other members of the Liliaceae. 5) Scanning Electron Microscope pictures of seeds revealed two main groups in the bulbous Liliaceae determined on the appearance of the cell walls of the testa. 6) A simple chromatographic technique was not found to be useful. 7) An investigation of chromosome numbers of. 44 samples of 15 species supplemented published data in allowing an analysis to be made of the application of chromosome numbers to generic concepts. Many genera of the Liliaceae - especially in the bulbous group - have extremely variable chromosome numbers. It is considered that numbers are more applicable to tribal than to generic concepts. Few indications of meiotic abnormalities were detected. Phylogenetic and taxonomic aspects of the genera of the bulbous Liliaceae are discussed and a key to the South African bulbous Liliaceae genera constructed. The following generic alterations are proposed: Ledebouria to be split off Scilla. Schizocarphus to be placed in Scilla. Resnova to be placed in Drimiopsis. The Astemme section (= Neobakeria) to be removed from Polyxena and placed in Massonia. The Cape species of Hyacinthus to be placed in Polyxena. Thuranthos, Urgineopsis and Urginea to be placed in Drimia. It is suggested that Schizobasis and Bowiea are of great importance in explaining the origin of Asparagus - possibly even directly from this group. In the generic revisions, thirteen genera are dealt with including typification, synonymy, distribution, field notes, species descriptions and keys. 67 species are dealt with, of which three are new (all in Ledebouria), and 31 new combinations are proposed.
- Full Text:
- Date Issued: 1973