78 Journal of Comparative Neurology. 



days. This last infiltration with thick collodion is exceedingly- 

 important, for upon its thoroughness the usefulness of the speci- 

 men depends. It is well to allow the collodion to become quite 

 thick before the final imbedding. When the process has been 

 carefully done it is an easy matter to cut even large sections lo 

 microns thick. 



Tissue is imbedded by placing it in a small paper box and 

 filling the box with thick collodion; the box is then placed in a 

 jar of chloroform which hardens the collodion. The object is 

 cleared and cut in the castor-thyme oil mixture : red oil of 

 thyme, 3 parts; castor oil, i part.^ 



Staining sections. — Nearly all of the usual staining fluids 

 gave good results. Of the hematoxylin stains Gage's, Her- 

 rick's, and Mallory's hematoxylin proved highly satisfactory. 



Forms selected. — Two forms have been chosen to illustrate 

 the development of the mammalian cerebellum. 



1. The Cat, a fairly representative mammal, from which 

 embryos of different ages may easily be obtained. 



2. Man whose brain is very highly specialized. An 

 attempt has been made to determine in what the essential differ- 

 ences and agreements consist. 



The cat was studied first, because its brain is less modified 

 than that of man. 



Plates. — All the figure's have been carefully drawn from 

 nature by the writer from his own dissections. Of the gross 

 preparations each one has been minutely examined by aid 

 of a lens and drawn at least twice ; indeed some have been 

 drawn several times. Detailed explanations will be given in 

 the description of plates. 



Those relating to the cat. Plates I and II, were studied 

 first and all except Figs, i, 2, 3, and were 23 drawn from care- 

 ful measurements. Figs, i, 2, 3, were outlined by the camera 

 lucida and 23 was photographed. 



Plate III shows sections of embryo kittens' cerebellums. 



ip. A. Fish. A new clearer for collodionized objects. Proceedings of the 

 American Microscopical Society, XV, pp. S6-S9, 1893. 



