ALBINO RAT BRAIN IN MULLER S FLUID 



413 



OBSERVATIONS 



If we consider the brains of pairs (rats of the same age, sex, 

 and litter, i.e., as similar as possible), there appears a very dis- 

 tinct tendency for the brains of older rats to gain more in Miiller's 

 fluid than do those of the younger rats. Table 1 presents fifteen 

 pairs arranged on the basis of their age. In ten of the fourteen 

 possible comparisons the brains of older rats gain more in twenty- 

 four hours. Also in ten of the comparisons the older brains 



TABLE 1 



Percentages of gain of pairs of albino rat brains arranged according to age and 

 weighed at intervals from twenty-four hours to seventy-five days 



gain more in seventy-five days, though this does not in every 

 case involve the same comparisons as were favorable to the 

 older rats at the twenty-four hour weighing. Table 2 presents 

 a summary of the data of table 1. The averaged figures for 

 the youngest three pairs and for the oldest three pairs are given. 

 The data show that age is a very important factor in the reac- 

 tion of the brain of the albino rat to Miiller's fluid. 



Brain weight increases as a function of age, and there exists 

 between these two characters a very high coefficient of correla- 



