II. SIZE OF THE BODY AND ORGANS 



87 



When the percentage weight of the hypophysis on the 

 weight of the brain (data for brain weight in tables 13 and 

 14 and for the hypophysis weight in tables 16 and 17) is com- 

 puted, the values obtained are represented by the graphs in 

 chart 18. These graphs show the percentage value of the 

 hypophysis to be higher in the female than in the male, but 

 on the whole the graphs for both sexes are nearly horizontal, 

 indicating a constancy in the percentage values. 



To determine whether the weight relations of the hypophy- 

 sis in the captive Grays have been changed from those shown 

 by the wild strain, the weights for the former have been com 

 pared with those for the latter as given in table 205. When 





Chart 18 Percentage weight of hypophysis on observed brain weight in 

 captive Grays both sexes. , male; , female. 



the data in that table are revised in terms of body length, it 

 appears that the weight of the hypophysis in the captive 

 Grays runs above that for the wild strain by about 7 per cent 

 in the males and 11 per cent in the females. Thus, the weight 

 of the hypophysis has apparently increased slightly in both 

 sexes of the captive Grays. This is a shift toward the albino 

 values. At the same time the weight relations according to 

 sex remain in the captive Grays similar to those found in tin- 

 wild strain, and the female hypophysis shows no tendency to 

 the very heavy weight characteristic of the albino females. 



ON THE WEIGHT OF THE THYROID IN THE CAPTIVE GRAYS 



Standards : Reference table 148 for the Albino and tall*- 

 204 for the wild gray Norway. The thyroid has about the 

 same weight in the wild gray Norway and the Albino. 



The percentage deviations in the weight of the thyroid are 

 given in tables 19 and 20. The graphs appear in chart 19. 



