lOO HUNTER. [Vol. II. 



ming, Plermann, Von Rath, and aqueous or alcoholic solutions 

 of corrosive sublimate gave uniformly favorable results. Speci- 

 mens were left in Flemming or Hermann from one to two 

 hours, and in corrosive from one-half an hour to six hours, 

 according to the size of the specimen. The shorter periods 

 gave better results. The method of Von Rath was somewhat 

 modified. Specimens were left in his picro-acetic-platini- 

 cosmic mixture from one to four hours, washed six hours in 

 methyl alcohol, twenty-four hours in pyroligneous acid, and 

 several days in weak alcohol, before leaving permanently in 

 95^. Such specimens, passed through xylol or oil of bergamot, 

 imbedded in paraffin, and cut from two to three mia^a thick, 

 gave the most satisfactory results, especially when stained in 

 Heidenhain's iron-haematoxylin. Of the other killing fluids 

 used I found Lang's fluid, Gilson's mixture, and Perenyi gave 

 the most satisfactory results. Chromic, chrom-acetic, chrom- 

 nitric, and corrosive-acetic mixtures shrink the cell-body badly, 

 giving it a vacuolated and fibrillar appearance. Formalin (ex- 

 cept in very weak solution), picro-formalin, and picric mixtures 

 were of even less value, destroying the cell elements greatly. 

 As stains, Heidenhain's iron-haematoxylin, with safranin and 

 Biondi-Ehrlich as controls, were employed for general work. 

 The methylen blue-eosin mixture of McClure, and cyanin and 

 erythrosin were used to demonstrate the chromophilous sub- 

 stance in the nerve cell. To demonstrate the structure of the 

 cell prolongations and nerves, thin sections were stained from 

 two to three days in iron-haematoxylin and the stain only partly 

 drawn out. This method gave very favorable results. 



Structure of the Nerve Cell. 



The cells of the so-called brain differ greatly in size, the 

 largest being situated most peripherally, the smallest most 

 internally. The largest ganglion cells measure 12 viicra X 16 

 micra, and have a nucleus measuring 4 micra X 9 micra. Those 

 of medium size, composing the greatest number of cells in the 

 ganglion, average 7 micra X 14 micra, with nuclei measuring 3 

 micra X 6 micra. The smallest cells are 3 to 4 micra across. 



