GÖMÖRI1 and Takamatsu2 in 1939 showed that the presence of phosphatase can be demonstrated in tissue sections. Their work referred to alkaline phosphatase; however, later, Gömöri3 described a method by which acid phosphatase, too, can be made visible in sections. Wolf, Kabat and Newman4 examined the nerve tissue for acid phosphatase. They found that it contains large amounts. With proper technic, normal nerve cells, as well as nerve fibers, may give a strong positive reaction. Hard and Lassek5 utilized the method for examination of growing axons and of degenerating nerve tissue. They found that tracts which become myelinated early exhibit enzyme activity early and that those which become myelinated late, such as the pyramidal tract, show phosphatase late. If a tract degenerates, the entire degenerating field gives a strong positive reaction for acid phosphatase. The authors discuss the possibility that the enzyme may be liberated