108 



ANATOMY 



In the inbred strain (Dr. King) the size of both the cells and 

 the nuclei was slightly greater in the female. On the other 

 hand while the nuclei are but little smaller than in the standard 

 strain, the cells have but 80 per cent of the diameter and there- 

 fore only half the volume of those in the standard strain. The 

 nucleus-plasma ratio is correspondingly reduced. 



Technical methods. To determine the effects of various fixa- 

 tives on the brain of the rat, King ('10) carried through a series 

 of weighings of mature rat brains which had been subjected to 

 the action of various fixatives. A summary of tli? results is 

 given in table 72. 



TABLE 70 



The solution of Ohlmacher ('97), the formula for which is as 

 follows : 



Absolute alcohol, 80 parts. 



Chloroform, 15 parts. 



Glacial acetic acid, 5 parts. 



Corrosive sublimate to saturation (about 20 per cent) was 

 found to give excellent results with the cells of the cerebral 

 cortex. 



In a later study King ('13 a) followed in some detail the 

 effects of formaldehyde on the brain of the Albino. The con- 

 clusions reached were as follows: 



1. A 4 per cent solution of formaldehyde causes a pronounced swell- 

 ing in the brains of rats of all ages. 



2. A solution of formaldehyde undergoes some chemical change on 

 standing, since a solution five months old causes less swelling in the 

 brain of the rat than does a freshly made solution. 



