ALBINO RAT BRAIN IN MULLER .S FLUID 



415 



curves and think of the rise and fall in percentage of increase as 

 periods more subject to individual variation. 



While increasing age presupposes increase in brain weight, it is 

 apparent that these two — age and brain weight — act as oppos- 

 ing factors in the determination of the reaction of the brain to 

 Miiller's fluid. That is, the older brains (these are heavier) 



TABLE 3 



The effect of initial brain weight — albino rat — on the percentage of gain of paired 

 brains. Pairs arranged according to age. Deviation of the lighter brain 



gain more than do the younger ones; yet the lighter brains gain 

 more than do the heavier ones if we can eliminate age as a fac- 

 tor, as was done in table 3. The curve of increase in weight 

 may be considered as capable of solution into at least two curves 

 — expressing these two factors. Age appears to be by far the 

 more potent factor. 



