GROWTH OF THE FETAL CENTRAL NERVOUS SYSTEM 453 
(obtained by sectioning) show an absolute volume of 0.034 ce. 
at approximately the close of the first month, while his two 
largest fetuses (new-born) have a cord volume of about 3 ce. 
The percentage increment of the spinal cord volume when de- 
termined for 5-cm. intervals of crown-heel body length (fig. 26, 
7d = 
14 
13 
Le 
ia 
fo a vorleee 
al . eee e 
éL aicactatens 
0) Lee tl cine ail, acl 
OND: 10 15 £0 £5 30 355 40 45 5O) 755cmn: 
Fig. 19 Field graph and curve of the growth of the midbrain in fetal life as 
shown by the colliculi length. Abscissa: total body length in em. Ordinate: 
colliculi length in em. Individual cases indicated by solid dots. Curve drawn 
totheformula: Y = 0.015X + 0.47. (Data from tables 29 and 30.) 
curve X) is 47 per cent for the 10-to-15-cm. interval. It rises to 
about 55 per cent for the 15-to-20-em. interval, and then falls to 
about 25 per cent for the 50-to-55-cm. interval. 
The percentage increment of the spinal cord volume when 
calculated for fetal months (fig. 28, curve I) shows a rate of growth 
of approximately 94 per cent in the fourth month and then de- 
scends steadily to 26 per cent in the last fetal month. 
