44 



NOBUHARU SUITSU 



factor 0.0344, which makes identical both the brain area and the 

 callosal area at the body weight of 274.8 grams. Column F of 

 table 2 shows the reduced values. The difference between the 

 reduced values of the total brain and the callosal area are repre- 

 sented in column G (F-E). These differences increase rapidly 

 from a body weight of 7.6 grams as the age advances and they 

 reach the maximum (F-E = 0.91) at a body weight of 27.4 

 grams, then decrease slowly, at last reaching point at the body 



50 100 ISO 200 250 



Chart IB In the upper curve the broken line shows the total brain area, 

 according to body weight as calculated bj' the formula ( v brain weight)^ X 0.0344 

 in order to make these two curves comparable at the last entry. In the lower 

 curve, the continuous line shows the area of the corpus callosum according to 

 body weight as calculated by formula 1. Albino rat. 



weight of 274.8 grams. The course of the ordinate differences 

 may be divided into three phases: 



Phase 1 (from sixth to tenth day). This represents small 

 differences from 0.16 to 0.37 mm. 2* 



Phase 2 (from tw^elfth to thirty-fifth day). The maximum 

 difference is 0.91 mm.^, the initial 0.82, and the final 0.83 mm.^ 



* From birth to six days the reduced brain area is smaller than the callosal 

 area. This anomalous result is chieflj^ due to the fact that the calculated rather 

 than the observed brain weights were used. I take this discrepancy to be the 

 result of computation. 



