GROWTH OF THE FETAL CENTRAL NERVOUS SYSTEM 449 
At 13 em. (C H) the absolute midbrain volume is about 0.2 ec., 
and this steadily rises to 0.75 cc. at 30 cm. (C H). From this 
point the absolute volume increases at a faster pace to about 
2.5 cc. at 50 cm. (C H). 
SOMES Sem: 
Fig. 17 Field graph and curve of the growth of the midbrain in weight and 
volume in fetal life. Abscissa: total body length in cm. Ordinate: midbrain 
weight and volume in grams (cc.). Individual cases indicated by solid dots 
(for weight) and by circles (for volume). Curve drawn to the formula: Y = 
0.01 [(0.168X)2-5§ + 12.0]. (Data from tables 27 and 28.) 
The volume of the midbrain, when calculated for age in fetal 
months (fig. 35, curve ITI), is about 0.15 cc. at the third month 
and increases to about 0.8 cc. at six months. Thereafter it 
grows slowly to about 2.5 ce. at birth. 
