198 Journal of Comparative Neurology and Psychology. 



though they had not yet returued to the normal size by the tenth day. 

 By the fifteenth day more than half the cells had disappeared, while 

 at the end of thirty-five days there was not a trace of a cell to be 

 found in the position of the nucleus of origin of the affected nerve. 

 The author believes that while, in case of section of a nerve, the cells 

 of origin enter upon a phase of reaction, this is followed by recupera- 

 tion; but in "arrachment" the phase of reaction is followed by pro- 

 gressive atrophy of the cell. 



Following poisoning by arsenic 8oukhanoff finds that changes 

 of varying intensity appear quickly in the spinal cord and spinal gang- 

 lia, and that in many preparations scarcely a normal cell would be 

 found. The lesions of the cell body were marked by diffuse colora- 

 tion, by loss of regular contour of the chromatic bodies and by turges- 

 cence of the cell. More accentuated lesions w'cre characterized by 

 clear spots around the periphery of the cell, owing to the loss of chro- 

 matic substance. This was followed by a still more marked lesion ex- 

 pressed by vacuolization of the cytoplasm. The degree of vacuoliza- 

 tion varies with the duration of the poisoning. Soukhanoff finds no 

 evidence of peripheral chromatolysis which has been described by 

 other authors as characteristic of arsenic poisoning. In the nucleus 

 there appears a diffuse coloration, obscurity of the nuclear membrane 

 and shrinkage. 



In his paper upon the finer structure of the nerve cell, van 

 Gehuchten ('97) took the position that chromatolysis is essentially a 

 dissolving of the tigroid substance. This results in turgescence of the 

 cell which, beginning at the center, mechanically forces the nucleus 

 towards the periphery of the cell, and causes expansion of the cell. A 

 reconstruction of the chromatic bodies reverses the process. Van 

 DuRME ('01) explains the turgescence of the cell during chromatolysis 

 upon the hypothesis that the katabolic products in the cell, notably 

 sarcolactic acid, increase the osmotic power of the cell and that this 

 produces turgescence. 



Chromatolysis itself, van Gehuchten ('97) holds, need not be 

 considered as a lesion in the cell. He suggests also, through van Bierv- 

 LiET ('99), that chromatolysis is, in a sense, a return of the cell to 

 the embryonic condition : that is to say, a condition in which the 

 chromatic substance exists in solution. Van Biervliet also concludes 

 that chromatolysis is perfectly compatible with the normal activities of 

 the cell. De Beule ('01) believes that all nerve cells which undergo 

 a non-physiological excitation, which may be traumatic, physical or 



