Note 89 — Chapter II · THE FUNCTIONAL RELATIONS OF THE NERVOUS SYSTEM.

It has been proved that the cells of the cornea and the pigment cells of the skin contract under nervous excitation. We cannot suppose that although these are the only cells which have hitherto been brought under experimental observation, they are the only cells subject to nerve-influence. We may safely assume that wherever a nerve-fibre terminates, its action will be transformed into an excitation of the part. Habitually, however, motor-nerves are spoken of as muscle-nerves.