NERVOUS SYSTEM 



53 



TABLE 36 



Percentage weight increase in rats' brains, each kept for ten weeks on 40 cc. of a 

 neutralized solution of 4 per cent formaldehyde made five months before the experi- 

 ments began (averages for three brains at each age) 



Maximum weight increase. 



TABLE 37 



Percentage weight increase in rats' brains, each kept for ten weeks in 40 cc. of a 

 neutralized solution of 4 per cent formaldehyde made at the time the experiments 

 began (averages for three brains at each age) 



AGE OF BATS 



Maximum weight increase. 



