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. The present study has two parts. In the first (Chapters 2 an 3) Fisher's theory of sex ratio is extended and in the second (described in Chapters 4, 5 and 6) the methods of quantitative genetics were applied to a laboratory population of Drosophila melanogaster to evaluate the amount of genetic variance in sex ratio. In Chapter 2 the relationship between birth control, sex preference and sex ratio was considered. It has been suggested that in some human populations the desire for male or female offspring coupled with the knowledge of methods of birth control can influence the distribution of family sizes. The consequences of this situation have been analysed using the evolutionarily stable strategy concept. . In Chapter 3, using precise genetic models, I have studied the evolution of the sex ratio in a population in which interactions between siblings exist but these interactions are not symmetrical with respect to the sexes. Some interesting differences between cooperative and aggressive models have emerged. The second part of the thesis is composed of three experiments. Experiment I was designed for investigation of the variability in the sex ratio character and identification. of the sources of heterogeneity apart from that due to binomial sampling. The results showed a close agreement with the expectations from random segregation and indicated that genetic or environmental factors affecting sex ratio were virtually absent. It has been reported that environmental factors can "distort the sex ratio in several species. One such factor is the age of parents. Experiment II was performed to study this suggestion in Drosophila melanogaster in the hope of obtaining some information about the mechanisms involved in this distortion. The data indicated that this phenomenon, at least in D, rosophila melanogaster is non-existent. In Experiment III artificial selection for sex ratio was performed. Nine generations of selection were unable to increase the sex ratio of the population. Selection was very effective in increasing the number of females, but the presence of sex-linked lethals was shown to be responsible. It was concluded that all of the empirical evidence supports a Mendelian interpretation and gives no support" to any theory invoking" adaptive sex ratio.

In this thesis, a case study approach has been used to investigate the planning and implementation of urban development at local level in the periphery of Barcelona, Spain. From a review of existing literature on the case study research methods in the social sciences, certain guidelines for the research design emerged. A conceptual framework was first assembled, from which research hypotheses were derived, to act as a loose analytical framework within which case study findings could be considered. The conceptual framework incorporates a review of the planning, legislative and developmental backgrounds; and the nine postulated hypotheses concern three interrelated aspects of planning and implementation: planning and control mechanisms, agency roles and activities, and the decision-making process itself. The actual case study method focuses on the compilation, structuring and analysis of three case study 'data-bases', comprising on-file documentation, plans, photographs etc obtained from local planning authorities and development agencies. First-hand accounts from agency personnel were also taken into account in the interpretation of data. The thesis makes a contribution to knowledge in the subject area in two ways. First, the research findings break new ground as regards existing literature on the development process in Spain. The case studies, both individually and collectively, provide new inSights into how and why the planning system failed in its statutorily attributed planning and control functions at local level; and conceptualization and analysis of decision-making in the case studies provide new perspectives on the Spanish planning process. Second, the development and application of a case study research method to investigate the functioning, at local level, of one of Europe's lesser developed planning systems, provides scope for the subsequent adaptation and use of this method for the monitoring and exchange of urban management experience in different planning environments and the conduct of international comparative research.

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This research is focused on the issue of urban development within the context of regional planning in Thailand. The study's main question is how national policy should attempt to shape the emerging urbanisation pattern in Thailand. In the past the country's development plans have emphasised industrialisation which has led to an acceleration in the growth of Bangkok, creating a dual economy and widening regional disparities. The Government's past efforts to decentralise economic activity have been relatively ineffective. This thesis considers a new approach, using the public service sector as the leading economic base for the development of a selected regional centre, Chonburi, in the Eastern Seaboard Sub-region. The study's analysis indicates that it is economically and administratively feasible to implement a Government work dispersal scheme. The analysis also indicates the necessity of controlling the large regional leakages which would otherwise reduce the regional multiplier effects. Overall, the study confirms that a growth pole approach can be initiated by public employment relocation and suggests that there is a viable alternative to nearly all of Thailand's growth being concentrated in Bangkok. However, the study also confirms that if private investment in the growth pole is to be achieved, this approach must be supplemented by long term public investment commitments and subtle co-ordination of private and public programming and planning measures.

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