FORMULAS 285 



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 (9) 

 and (10) 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 144 were obtained. 



AREA OF CALLOSUM (SuiTsu, '20) 



The theoretical curve, about which the observations cluster, is 

 represented by the continuous line in chart 8 and was computed 

 by means of the formula : 



y = 0.184 + 0.0003 x + 2.08 log x (11) 



in which y is the area of the callosum in the sagittal section, in 

 millimeters, and x the weight of the body, in grams. This 

 formula is based on the general formula y = a + bx + c log x, 

 already published by Hatai ('11). 



CRANIAL CAPACITY (DONALDSON, '12) 



For the cranial capacity expressed in cc. the formula for 

 sexes combined is 



Cranial capacity in cc. = 



1.02 log Bd. wt. - 0.00027 Bd. wt. - 0.596 (12) 

 [80 < Bd. wt. < 300] 



SPINAL CORD WEIGHT ON BODY WEIGHT (DONALDSON, '09) 



Spinal cord wt. (sexes combined) = 



0.585 log (Bd. wt. + 21) - 0.795 (13) 



In the female the spinal cord is about 2 per cent heavier than 

 in the male, therefore when using formula (13) the values ob- 

 tained require to be increased by 1 per cent to represent the 

 weight of the spinal cord in the female and to be diminished by 



