418 



JAMES STUART PLANT 



TABLE 5 



Averaged percentage weight relations of the parts of four albino rat brains during 

 the course of their reaction to Miiller's fluid 



WATER RELATIONS 



We have studied the water relations after seventy-five days in 

 fifty-nine whole brains and after thirty days in the parts of three 

 brains. There is evidently, in' the reaction of the brain to the 

 Miiller's fluid, a deposition of salts in the brain tissue. This is 

 shown in table 6. Part A deals with the fifty-nine whole brains; 

 Part B with the parts of three brains (all belonging to young 

 females). The deposition of salts at the end of seventy-five 

 days in the whole brain is from 3.9 per cent to 4.3 per cent of 

 the total water of the brain despite the fact that the salts in 

 Miiller's fluid are present in a concentration of but 3.5 per cent. 

 This shows a deposition of salts in the tissues. If, in addition, 

 there is some diffusion of solids from the brain to Miiller's fluid — 

 and, from inspection, this appears to be the case — the percent- 

 age of salts deposited must be even higher than that indicated 

 by the figures given. 



The final percentage of water in a given brain at the seventy- 

 five-day weighing is only slightly greater than that of a fresh 

 brain belonging to a rat of the same age, sex, and litter. In 

 view of the 20 to 30 per cent net increase in weight in Miiller's 



