GROWTH OF THE CORPUS CALLOSUM 



57 



If the callosum of the rat brain at five days of age is similar 

 in development to that of man at birth, and the growth pro- 

 cesses in the rat are thirty times as rapid as in man, then the 

 stage of completion of the callosal growth which occurs in the 

 rat brain at about twenty-five days should occur in the human 

 brain at about twenty months of age. This conclusion has not 

 yet been tested. 



TABLE 8 



Showing the relation between development of the myelinated fibers in the callofntm 

 and the psychical development of the albino rat 



The data on the 'psychical development' are derived from the tabulation by 

 Allen ('04) based on the data of Small and Watson. 



