214 



1) 10°/ solution of formol. 



2) Saturated aqueous solution of corrosive sublimate. 



3) Flemming's stronger chromic-osmic-acetic fluid. 



4) Potassic bichromate, gradually raised from 2°/ to 5°/ solution. 

 Many stains fail to bring out clearly the giant cells and their 



neuntes, though staining other parts of the nervous system well. This 

 is particularly true of the carmine stains. 



The Golgi and methylen-blue methods were tried exhaustively on 

 fresh material, but no impregnation of the giant cells was obtained, 

 although by the Golgi method excellent impregnations of the other 

 nerve elements were secured. 



The following stains, in the order named, proved to be the most 

 valuable: — 



1) Kenyon's copper sulphate-phosphomolybdic acid hematoxylin, 

 following preservation in formol. 



2) Heidenhain's iron hematoxylin, used on formol or sublimate 

 material. 



3) Sahli's methylen-blue-acid fuchsin axis - cylinder stain, used 

 on bichromate material. 



4) Double staining with Ehklich's acetic acid alum hematoxylin, 

 and congo red, or acid fuchsin. 



The first method proved to be of the greatest value, and as this 

 is, I believe, the first time, that it has been used on vertebrate material, 

 it deserves a word of comment. Material killed in 10°/ formol and 

 preserved in 5°/ formol was washed in water and put in a 5% solution 

 of copper sulphate for 24 hours, by which time it had assumed a green 

 color. After cutting in paraffine and mounting in the usual way, the 

 sections were stained on the slide from 15 to 30 minutes, in the fol- 

 lowing mixture: — 



10°/ o Phosphomolybdic acid ... 1 cm. 



Hematoxylin crystals 1 grm. 



Chloral hydrate 10 grms. 



Water 400 cm. 



They were then rinsed in water, dehydrated, cleared and mounted 

 in the usual way. This is an excellent differential stain for nerve 

 fibres, neuroglia, and the dendrites of ganglionic cells. 



