846 DEVELOPMENT OF THE HUMAN BRAIN. 



also established by the above-mentioned Dutch Ana- 

 tomists, since they found that the weight of the Cere- 

 brum in the new-born infant was to its weight in the 

 adult as 96 : 157 ; while the weight of the Cerebellum in 

 the new-born infant was to its weight in the adult only 

 as 22 : 50. 



The actual ratio of the weight of the Cerebellum to 

 that of the Cerebrum in the new-born infant was found 

 by Chaussier to vary from 1 : 13 to 1 : 26 ; and by Cruvel- 

 hier it was ascertained to be 1 : 20. On the other hand, 

 according to Sharpey, the ratio of the weight of the Cere- 

 bellum to that of the Cerebrum in the adult male is 1 : 8y, 

 and in the adult female, 1 : 8J. 



From these figures it may be seen how very considerably 

 the development of the Cerebellum lags behind that of the 

 Cerebrum in the Human Infant at the time of birth. 



In regard to the microscopical characters of the foetal 

 brain one brief but important statement deserves to be 

 recorded. 



According to Lockhart Clarke*: "In the early foetal 

 brain of Mammalia and Man the structure [of the cere- 

 bral convolutions] consists of one uninterrupted nucleated 

 network. As development advances separate layers may 

 be distinguished." But even in these layers there are 

 only to be recognized " roundish nuclei connected by a 

 network of fibres," or, in other parts, groups of more 

 elongated nuclei, in place of the distinct but differently 

 shaped Nerve Cells with inter-connecting processes, which, 

 in a later chapter, will be described as the prevailing and 

 characteristic constituents of the Cerebral Convolutions in 

 their developed condition. 



* "Notes of Besearches on the Intimate Structure of the 

 Brain," Proceed, of Royal Society, 1803, p. 721. 



