GROWTH OF THE FETAL CENTRAL NERVOUS SYSTEM 419 
The percentage increment, when calculated for time, is about 
600 in the fourth fetal month. This drops to 185 in the fifth 
month and to 22 per cent in the tenth month. 
a SE ae ae OS Ge Oma”. OR Oa 
Fig.2 Field graph and curve of the growth of the central nervous system in 
fetal life. Abscissa: total body length in cm. Ordinate: central nervous system 
weight and volume in grams (cc.). Individual cases are indicated by solid dots 
(for weight) and by circles (for volume). Curve drawn to the formula: Y = 
(0.114X)334 + 2.0. (Data from tables 1 and 2.) 
Growth of the encephalon 
The curve of the absolute volume of the entire brain (fig. 3) 
when based on crown-heel length is a concave curve expressed by 
the empirical formula: 
Encephalon volume (cc.) = (0.125 (C Hlength cm.))#6 + 1.5 
