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
Studies on the ecology and molecular biology of transferable drug resistance factors in coliform bacteria
- Authors: Marcos, David
- Date: 1973
- Subjects: Enterobacteriaceae , Molecular biology , Microbial ecology , Bacteria -- Ecology , Ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4249 , http://hdl.handle.net/10962/d1007494 , Enterobacteriaceae , Molecular biology , Microbial ecology , Bacteria -- Ecology , Ecology
- Description: From Introduction: It was as early as 1904 that Paul Ehrlich propounded the idea of a “magic bullet”. This “magic bullet”, or chemotherapeutic agent, as he also called it, had to meet certain requirements: (a) a high activity against pathogenic micro-organisms; (b) easy absorption by the body; (c) activity in the presence of body fluids and tissue; (d) a low degree of toxicity; (e) must not allow the development of resistant micro-organisms. The discovery of the sulphonamide, Prentosil, by Domagk in 1935 was one of the initial steps in the search for this “magic bullet”. This, together with the production and purification of the antibiotics penicillin, by Fleming, Florey and Chain in 1942 and streptomycin, by Waksman in 1943, heralded a new era in the fight against bacterial infections. The majority of modern antibacterial agents have to a large extent met the requirements of Ehrlich’s ‘magic bullet”. They have however failed to prevent the development of resistant bacterial strains. This has been particularly noticeable in the past twenty years since the sudden emergence of multiple-resistant bacteria, many of which can transfer to several drugs in one step by a process of conjugation. This phenomenon which has serious medical implications has prompted numerous studies on the origin, epidemiology, biochemistry and genetics of transferable drug resistance.
- Full Text:
- Date Issued: 1973
- Authors: Marcos, David
- Date: 1973
- Subjects: Enterobacteriaceae , Molecular biology , Microbial ecology , Bacteria -- Ecology , Ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4249 , http://hdl.handle.net/10962/d1007494 , Enterobacteriaceae , Molecular biology , Microbial ecology , Bacteria -- Ecology , Ecology
- Description: From Introduction: It was as early as 1904 that Paul Ehrlich propounded the idea of a “magic bullet”. This “magic bullet”, or chemotherapeutic agent, as he also called it, had to meet certain requirements: (a) a high activity against pathogenic micro-organisms; (b) easy absorption by the body; (c) activity in the presence of body fluids and tissue; (d) a low degree of toxicity; (e) must not allow the development of resistant micro-organisms. The discovery of the sulphonamide, Prentosil, by Domagk in 1935 was one of the initial steps in the search for this “magic bullet”. This, together with the production and purification of the antibiotics penicillin, by Fleming, Florey and Chain in 1942 and streptomycin, by Waksman in 1943, heralded a new era in the fight against bacterial infections. The majority of modern antibacterial agents have to a large extent met the requirements of Ehrlich’s ‘magic bullet”. They have however failed to prevent the development of resistant bacterial strains. This has been particularly noticeable in the past twenty years since the sudden emergence of multiple-resistant bacteria, many of which can transfer to several drugs in one step by a process of conjugation. This phenomenon which has serious medical implications has prompted numerous studies on the origin, epidemiology, biochemistry and genetics of transferable drug resistance.
- Full Text:
- Date Issued: 1973
The effects of soil fumigation, applied fertilizers and climate on the growth and nutrient levels of cayenne pineapples under field conditions
- Authors: Marr, George Stuart
- Date: 1973
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21067 , http://hdl.handle.net/10962/6246
- Description: From Introduction: The pineapple producing area of the Eastern Cape lies between 33°S and 34°S latitude. It is the most distant area from the equator in which pineapples are grown commercially, most other areas lying between latitudes 25°N and 25°S (Collins, 1960). The prevailing climatic conditions may be considered as being adverse to the growth of a plant which originated in the tropics. Girton, (1962) considers the area to be unsuitable for commercial production because of the cold weather experienced during winter. Seasonal fluctuations in growth and nutrient levels of the plant have been referred to by van Lelyveld, (1964), but these have never been studied locally. Because of the profound effect of temperature on the growth and nutrient requirements of any plant, it was deemed necessary to investigate the effects of the cooler conditions on the growth and nutrient levels of the pineapple plant, the results of which may give some indications of seasonal nutrient requirements.
- Full Text:
- Date Issued: 1973
- Authors: Marr, George Stuart
- Date: 1973
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21067 , http://hdl.handle.net/10962/6246
- Description: From Introduction: The pineapple producing area of the Eastern Cape lies between 33°S and 34°S latitude. It is the most distant area from the equator in which pineapples are grown commercially, most other areas lying between latitudes 25°N and 25°S (Collins, 1960). The prevailing climatic conditions may be considered as being adverse to the growth of a plant which originated in the tropics. Girton, (1962) considers the area to be unsuitable for commercial production because of the cold weather experienced during winter. Seasonal fluctuations in growth and nutrient levels of the plant have been referred to by van Lelyveld, (1964), but these have never been studied locally. Because of the profound effect of temperature on the growth and nutrient requirements of any plant, it was deemed necessary to investigate the effects of the cooler conditions on the growth and nutrient levels of the pineapple plant, the results of which may give some indications of seasonal nutrient requirements.
- Full Text:
- Date Issued: 1973
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