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The production of the isoflavonoid phytoalexins medicarpin, sativan and vestitol by lucerne (Medicago sativa L) in response to substances, named elicitors, released into culture fluids of the plant-pathogenic fungus Verticillium albo-atrum was investigated. Methods for establishing the production of phytoalexins were studied and developed to use for screening substances from culture filtrates for elicitor activity. A method of reverse-phase High Performance Liquid Chromatography was developed in order to obtain quantitative measurements of elicitor activity. The presence of elicitors in extracts of the mycelium of the fungus was also investigated. Attempts were made to isolate and purify the component(s) from culture filtrates and mycelial extracts of Verticillium responsible for elicitor activity. Activity was not removed from culture filtrates by dialysis. Studies were made initially using Sephadex G-200 gel chromatography and anion exchange chromatography. Subsequently, the culture filtrate elicitor was found not to be precipitated in 80% v/v ethanol while inactive components were. Biogel P-10 chromatography produced an apparently homogeneous fraction on which preliminary chemical studies were performed. A molecular weight of 3000-4000 was indicated for the material. This fraction proved capable of further resolution. Cation and anion exchange chromatography was used for this purpose. The most active fraction obtained was retained by the anion exchanger but not a cation exchanger. This could be resolved by analytical scale reverse-phase liquid chromatography into multiple components. Colorimetric assays showed the material to be predominately peptide although a small amount of carbohydrate was present. The most active material from mycelial extract was not retained by either cation or anion exchangers. Colorimetric assays showed it to be predominately carbohydrate although protein was also detectable.

This thesis is concerned with two fields of study, namely that of the subdivision of an urban area into relatively homogeneous residential areas, an area of study known as social area analysis; and secondly the study of juvenile delinquency from a geographical perspective. After providing an evaluation of the theoretical and methodological bases of social area analysis, the study analyses the structure of Swansea, Cardiff and Newport by using multivariate techniques to analys data drawn from the 1966 Population Census. The measures which result from this analysis are described and compared with those produced by similar studies conducted in Britain and in other countries so that the distinctiveness of the results of this study and of British studies in general may be assessed. The spatial distribution of the principal classificatory measures are related both visually and by means of statistical techniques to a model of the structure of the British city; the results being compared with the patterns produced by similar British and non-British studies. A social area typology is produced and the categories within it are described for each of the study areas. The social area typology produced for the Cardiff study area acts as a backcloth for the further study of the incidence of juvenile delinquency. The incidence of juvenile delinquency in Cardiff is analysed, first, in spatial terms by the calculation of a number of offender indices for three different time periods. Some consistency in the distribution of the indices is apparent and "delinquency areas" are identified in particular parts of Cardiff. Second, two of the offender indices are related to a number of environmental indices, and a number of ecological associations are established by a variety of statistical techniques. In particular the strength of the association between the incidence of juvenile delinquency and low socio-economic status is noted. Finally social surveys conducted in relatively delinquent and relatively non-delinquent sample areas are used to test certain hypothesis derived from theories concerned with the explanation of the incidence of juvenile delinquency. Of the hypotheses tested greatest empirical support is provided for the sub-cultural hypothesis.