CELL CHANGES IN THE CENTRAL NERVOUS SYSTEM UNDER VARIOUS NATURAL AND EXPERIMENTAL CONDITIONS. THIRD PAPER: FUNCTIONAL ACTIVITY

1. Varying degrees of functional activity and fatigue were induced in white rats by prolonged swimming. 2. Microscopical examination of Nissl preparations from the cerebellum, cervical cord, and spinal ganglia revealed mild but demonstrable nerve-cell alterations. 3. These were strikingly similar in character to those previously observed in parathyroid tetany dogs and cretin lambs. 4. Chromatolysis is considered as a general reaction of nerve cells, which invariably occurs whenever the normal functional equilibrium of these units is disturbed. 5. This reaction varies in its intensity with the severity of the opposing influence, and to this extent only can it be spoken of as specific.