MATHILDE L. KOCH AND OSCAR RIDDLE 



Indeed, in the four really comparable 5 groups the lowest average 

 brain weight for males is higher than the highest average for fe- 

 males. The same is true for the two separate parts of the brain — 

 the male cerebellum-medulla is larger and the male cerebrum is 

 larger. 



That this larger size of the brain, and of both parts of the 

 brain, of the male is not wholly dependent upon the larger body 

 size of the male is indicated by the fact that two only of the male 



TABLE 3 

 Details on the materials used in the preparation of groups V and VI 



1 Known to be ataxic. 



groups are larger and two are smaller than the associated females. 

 For the mature birds the brain weight shows considerable inde- 

 pendence of body weight. 



The relation of age to the size of the brain and to each of the 

 two parts into which we have divided it can be partly under- 



6 Group VI is clearly immature; group V is not of the same strain. In the 

 latter group, moreover, the disparity of age is extreme; the males being very old 

 (nine years) and the females in their prime (three years). 



