IB 



been secured throu^,h the use of tlie chrome-oxalic mixture of 

 Graf ('9?). This reagent appears to have escaped the general 

 attention of microscopists, at least no mention is made of it 

 in the fifth edition of Lee (1900). The composition is here 

 given: 



Oxalic acid, 8% aq.sol. - - - 300 c.c. 



95? alcohol - - - - - - - 15 0C.C. 



Chromic acid, \% aq.sol. - - - 160 c.c. 



Mix in the order as named. 



Quite small pieces of the brain were fixed in this fluid 

 for six hours, and the fixing agent was then washed out with 

 '?0% alcohol. Sections were made by tlie paraffin method. 



The slide was taken from distilled water, and the steaming- 

 hot stain of Nissl was poured over the sections, five minutes. 

 The excess stain was rinsed away with distilled water for the 

 briefest possible time, and the water clinging to the slide 

 was absorbed with filter paper. Differentiation with the anilin- 

 aloohol of Nissl took but a few seconds, being stopped by flood- 

 ing with oil of cajeput just as soon as the sections took on a 

 delicate rose tint. Clearing with the oil of cajeput was aided 

 by holding the slide for a few mon.ents in gentle heat. Mount- 

 ing was done in colophoniuir dissolved in xylol. The staining 

 is remarkably precise, and the color has shown no tendency to 

 fade. 



The counter-staining methods described by Held ('95), 

 and by ITarrington ('99), were also applied, with certain modi- 

 fications found necessary. The erythrosin mixture of Held 



