288 Journal of Comparative Neurology and Psychology. 



fluid, picro-formalin, van Gehuchten's fluid, corrosive sublimate and 

 chrom-oxalic acid showed more or less shrinkage of the cytoplasm aud 

 injury to its finer structure. In all the cells of these preparations a 

 central, darkly staining, granular region was demonstrated, and a peri- 

 pheral zone formed by a network of fibrillae. In the nerve fibers the 

 fibrillae also exhibited anastomoses. Fresh, living ganglia, stained 

 with Xissl's methylene blue and studied in normal salt solution, 

 showed Uttle or no shrinkage of the cytoplasm. They were entirely 

 devoid of a cell membrane, and though the filn-illar networks were 

 clear and distinct, there was no evidence of the darkly staining gran- 

 ules characteristic of fixed tissues. This normal structure was also 

 observed when ganglia were fixed by the vapor of formalin, and when 

 stained with methylene blue and fixed with amuKjnium moly])date ; 

 graded formalin and diffused alcohol are recommended for larger 

 masses of tissue. In agreement with Held, the author finds that the 

 chromophile granules (Nissl substance) are not normal structures ])ut 

 are formed in the cytoplasm both during post-mortem changes and 

 during the action of most fixing reagents. The substance is not de- 

 monstrated by staining after treatment with sodic hydrate nor after pro- 

 longed faradization ; })robably not after .strychnine poisoning. Arsenic 

 poisoning causes an increase in the amount of the substance present 

 in the cells. 



These observations are at variance with the results of Bethe and 

 VON Lenhoss:^k, who .saw the Nissl'.s plates in living nerve cells of 

 vertebrates. From various other points of evidence Bethe maintains 

 that the XissL substance is a normal product of the cells. It is un- 

 fortunate that the author did not have opportunity to study the fibrillar 

 structures which he describes by more specific staining methods. The 

 evidence of preparations obtained by Bethe's toluidin lilue method 

 would not support Dr. Floyd's statement that a general anastomosis 

 exists between the neuro-fibrillae of nerve fibers. 



The conclusions of this i)aper are of great value. They show 

 that most of the common fixing reagents cannot be depended upon 

 for the preservation of delicate nerve cell structures, and em- 

 phasize the necessity, too often overlooked, of studying fresh tissues 

 to control results obtained from fixed material. c. w. p. 



