162 GROWTH OP PARTS AND ORGANS 



Brain Weight on Body Weight. (Hatai, '09, p. 172) 



For the brain weight of sexes combined, the following for- 

 mulas have been obtained : — 



Brain weight (sexes combined) = 1.56 log (Bd. wt.) —0.87 (6) 



[5 < Bd. wt. < 10 gms.] 



Brain weight (sexes combined) = 



0.569 log (Bd. wt. - 8.7) +.554 (7) 

 [Bd. wt. > 10 gms.] 



For a given body weight the average brain weight in the male 

 was found to be 1.5 per cent more than in the female, hence the 

 determinations of brain weight on body weight by formulas (6) 

 and (7) give final values which must be increased by 0.75 per 

 cent to represent the male brain and decreased by 0.75 per cent to 

 represent the female brain weight. By using this procedure the 

 data on brain weight given in table 68 were obtained. 



Cranial Capacity on Body Weight. (Hatai, '07 c) 



Cranial capacity represented by the weight of the shot con- 

 tained is given by 



Cranial capacity (shot wt.) = 0.0072 X (Bd. wt. male) + 9.349 (8) 



To reduce the shot weight to brain weight in the male, the value 

 obtained is to be divided by 5.98. 

 The corresponding formula for the female is 



Cranial capacity (shot wt.) = 



0.0251 X (Bd. wt. female) + 6.168 (9) 



To reduce the shot weight to brain weight in the female, the 

 value obtained is to be divided by 6.009. 



