THE ENORMOUS increase in knowledge of the processes of synaptic inhibition and excitation obtained by neurophysiologists in the last decade provides ever deepening insight into the extraordinary complexity of reflex organization. In addition, a more detailed description of the intricate synaptic structures, revealed by electronmicroscopists, has coincided and made possible the development of this fundamentally new evidence concerning synaptic function. The demonstration of inhibitory and excitatory synapses, of electrical as well as chemical synaptic transmission with a variety of possible transmitter substances, and of differential electrical properties of postsynaptic elements, whether dendrites, somata, or axons, now offers physiologists an opportunity for meaningful discoveries of functional neuro-anatomical relationships. Since Pollock and Davis1,2 first described the cerebellar tonic control exerted upon vestibular reflexes, there have been several studies of the modulation of statokinetic reflexes by various central, inhibitory sources. The intriguingly complex pattern of interrelations between the individual vestibular nuclei and