Thirteen rhesus monkeys were subjected to impacts of either 200, 300, 400, oe 500 g-cm, on the dorsal surface of the spinal cord (Allen 1911). Six monkeys served as controls to determine the results of transection of the cord as well as the optimal survival time, and 2 additional subjects underwent the operative procedures only. Most of the animals were sacrificed 1 week postoperatively and the brains and spinal cords were processed by the Fink and Heimer (1967) technique for degenerating axons. Two contrils and 1 experimental subject, sacrificed at 1 week, were prepared for electron-microscopic analysis...