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This thesis examines certain aspects of the general hypothesis that 'sex hormones participate in the physiological regulation of carbohydrate metabolism'. Studies in female rats at different stages of the oestrous cycle, following ovariectomy and during advancing age indicate that enhanced sexual endocrine function is associated with an improvement of glucose tolerance and an elevation of plasma insulin levels. This interpretation is substantiated by observations that treatment of ovariectomized females with oestradiol, progesterone and a preparation of gonadotrophins produces similar alterations of glucose metabolism and the circulating insulin pool. Evidence is presented that oestradiol and progesterone induce these changes within six hours, and that progesterone, but not oestradiol may directly promote pancreatic insulin secretion within this period, Testosterone does not appear to exert a significant influence on glucose tolerance in male rats, although there is a tendency for this hormone to reduce plasma insulin levels. Characteristic sex differences of glucose tolerance and circulating insulin levels have been detected and their possible relationship with the prevailing sex hormone environment is discussed. The mechanisms through which sex hormones may effect glucose tolerance and insulin levels, and the implications of these processes are considered with respect to their importance during different reproductove states in the female.

Until a question on internal migration was included in the census, vague assumptions were made about drifts of the population and the effects of these on gaining and losing areas. This study attempts to show that drifts of the population, in a modem industrial society, are the exception to the rule. In fact, almost equal numbers of persons are 'exchanging' between areas and these persons tend to have similar characteristics. Because of this the largest proportion of migrants move between urban centres and no longer from rural to urban centres. Migration rates are high among persons who are well educated and who have career-type jobs. Persons in career and similar-type jobs expect to have to move frequently during the career cycle and consider advantages gained from each move in relative rather than absolute terms: relative to past, but also to possible future advantages. These persons are also less likely to seek mere instrumental advantages from their work situation. The change in the nature of modern-day migratory moves has a special effect on social mobility. Migrants into a large city no longer serve to facilitate upward social mobility of city dwellers but appear to compete actively with them for high status positions. Part of the reason for this is that many migrants have spent most of their lives in other large cities. But even those coming from small towns and rural areas appear to have better chances of upward social mobility than city natives who never move. Finally, it appears that the element of force in migrations in a modern industrial society is on the decline and that migration today is more a function of career pattern and life-cycle variables.