No. 2.] CHANGES IN NERVE CELLS. m 



Studied the changes in the central nervous system of animals 

 dying from varnishing the skin. A constant symptom, he notes, 

 is hyperemia of spinal cord and brain with numerous capillary 

 hemorrhages in the gray matter, especially of cord and medulla. 

 Extreme vacuolation is the most characteristic change in the 

 cells. 



An exhaustive research of Sadovski (73), under title, " On 

 the changes of nerve centres due to peripheral irritation," has 

 for its purpose " to ascertain whether pathological changes in 

 the centres can be induced by irritation of a nerve." He ac- 

 cordingly stimulates, or better, irritates a nerve, generally by 

 ligature ("from 10 to 71 days "), and thereby succeeds in causing 

 neuritis with formation of a "knot about the size of a pea" 

 and peripheral, not any central, degeneration of the nerve. 

 Microscopical examination of the ganglia, using those of the 

 uninjured side for controls, showed for most of the cells no dif- 

 ference. Many cells, however, on the operated side exhibited 

 great vacuolation and shrinking of protoplasm from the capsule. 

 The nuclei of the altered cells he describes as " oval instead of 

 round, densely stained, sometimes shrunken so as to leave a 

 space between nucleus and protoplasm, and zigzag in outline." 

 In later stages no trace of nucleus is present. In some of his 

 experiments Sadovski employs electrical stimulation, and it is 

 difficult to understand from the ground of my own experiments 

 how, in Group III, experiment 5, for example, a moderate stimu- 

 lation of only fifteen minutes daily for twenty-one days could 

 have produced the vacuolated protoplasm and shrunken and 

 atrophied nuclei that he describes for it (73, p. 30). The nerve, 

 auricularis magnus, in the ear of a dog was stimulated through 

 the skin. In explanation, Sadovski advances the view that any 

 such additional irritation causes the nerve cells to break down 

 more rapidly than they are able to recover, and a gradual 

 "atrophy" takes place. Hence he affirms "it is possible to 

 demonstrate morphological changes in nerve cells due to exces- 

 sive activity." He says nothing of «crw/^/ activity. 



Somewhat similar to the last is the research of Mrs. Ter- 

 nowski (80) upon " Changes in the spinal cord occasioned by 

 stretching the sciatic nerve." Among other things, such as 

 hyperemia, etc., vacuolation and atrophy of ganglion cells 

 is noted in both anterior and posterior horns. This is opposed 



