Postnatal Growth of the Human Brain 



117 



The mean deviation of the calculated from the observed averages 

 for the time intervals as given above is 28.4 grams, and the mean 

 percentage deviation is 2.68 per cent. 



The weight of the cerebellum from birth to 20 years (890 

 cases — 99 newborn and 791 between birth and 20 years) may 

 be represented by the formula : 



Age (yrs.) 



Cerebellum weight (gm.) — r 4- 19.8 



& vs ' 0.094 -f- 0.0078 age (yrs.) T 



The mean deviation of the calculated from the observed aver- 

 ages is 3.82 grams and the percentage deviation is 3.72. 



The empirical formula for the inspected weight of the pons, 

 medulla and midbrain (857 cases — 100 newborn and 757 be- 

 tween birth and 20 years) is : 



Age (yrs.) 



Pons, medulla aud midbrain weight (gm.) = - 4- 5.0 



to Vb ' 0.117 -f- 0.041 age (yrs.) ~ 



The mean deviation of the calculated values from the observed 

 averages in 0.25 gm. and the mean percentage deviation is 2.2 

 per cent. 



The accompanying graph illustrates the curves of postnatal 

 growth of the brain and its parts as drawn to the formulae given 

 above. 



