CHANGES IN HUMAN CEREBELLUM WITH AGE O 



Table 2 shows that at birth the cerebelhim is very small and 

 underdeveloped, being onh' about 5.7 per cent of the total brain 

 weight, while in the adult it has nearly double that percentage. 

 During the first year the cerebellum grows with great rapidity, 

 so that by the end of that time it has reached nearly two-thirds 

 its adult weight; by the end of the second year it has four-fifths 



300 



20 MONTHS Z4 



Chart 1 (Iraphs for the frrowth of the human encrphalon and cerebellum dur- 

 ing the first twenty-four months of life. The ordinate values differ for the three 

 records. On the ordinate at the left are the values for the weight of the cerebel- 

 lum: to the right for the weight of the cerebrum, and within the chart, at the 

 right, for the percentage weight of the cerebellum. The weight of the enceph- 

 alon is shown by the upper graphs: males; females. The weight of the cere- 

 bellum is shown by the middle graphs: males; females. The percentage weight 

 of the cerebellum is given for the first eighteen months by the lowest graph, 

 without distinction of sex. All the graphs have been smoothed. 



of its adult weight and the period of rapid growth is over. This 

 appears clearly from chart 1. 



As a result of its rapid growth, the cerebellum gains steadily on 

 the cerebral hemispheres until the tenth to twelfth months by 

 which time it has reached approximately its relative weight in 

 the adult. Xo very marked change in this relative weight is 

 found after the first year. 



