58 RELATIVE WEIGHT AND VOLUME OF COMPONENT PARTS OF FETAL BRAIN. 



These figures for the telencephalon are rendered even more striking when we 

 study the growth conditions of its various subdivisions. It was possible in all cases 

 to separate this structure into the neopallium and the archipallium. At 4.3 mm. 

 the undivided neopallium weighed 2.8 per cent; at 25 mm. 27.4 per cent; at 50 mm. 

 51.18 per cent, the curve continuing to mount rapidly to a maximum of 83.92 per 

 cent at term. At the stage of 50 mm. it was possible to isolate the corpus striatum 

 which weighed 12.67 per cent. From this point its weight-curve declines steadily 

 to a minimum of 4.8 per cent at term. The archipallium at 4.3 mm. weighed 4.2 

 per cent, twice the initial weight-value of the neopallium, reaching a maximum of 18 

 per cent at 7 weeks, from which point the weight-curve declined steadily to 1.03 per 



[J Telen 



cephalon 



I Mesencephalon 

 Cerebellum 



i; 



CHART 1. Diagrammatic representation of the percentage weights of the brain parts at different stages 



of development. 



