Variations in the amount of antidiuretic hormone secreted from the neurohypophysis are reflected as changes in the rate of urine flow from the kidneys. The evidence has already been discussed in the introduction to this thesis for the belief that the neurohypophysis is innervated from cells in the supraoptic nucleus; and that the integrity of the nervous connections between the supraoptic nucleus and the neurohypophysis is essential for the normal control of the rate of 'urine secretion.
Stimuli applied to the supraoptic nucleus, either directly, or indirectly, cause changes in the rate of urine excretion; thus these changes can be used to indicate the state of activity of the supraoptic nuclear cells.
The experiments reported in this thesis have lent further support to the view that acetyl choline stimulates the cells of the supraoptic nucleus. The results also give rise to many interesting speculations, the exact origin of which is obscure at present.
The supraoptic nucleus is a comparatively easily accessible central synapse, and in recording variations of the rate of urine secretion a reliable index of the state of activity of the cells is present.
It is likely that further work on these lines may provide important information as to the behaviour of central synapses.