GROWTH OF THE FETAL CENTRAL NERVOUS SYSTEM 445 
The pons length also shows some interesting changes in the 
course of fetal life. The graph of absolute pons length plotted 
against total body length (fig. 16) is practically a straight line 
having the formula: 
Length of pons (em.) = 0.0263 C H body length (em.) + 0.16 
Fig. 15 Field graph and curve (connecting the average points of each 5-cm. 
crown-heel interval) of the per cent which the volume of the pons and medulla 
forms of the encephalon volume. Abscissa: total body lengthin cm. Ordinate: 
pons and medulla volume in per cent of the entire brain volume. Individual 
cases indicated by solid dots. (Data from table 40.) 
The length increases steadily from 0.42 em. at 10 em. (C H) to 
about 1.53 cm. at birth (50 em. C H). 
When plotted against time, the pons length increases rather 
rapidly from the third to the beginning of the sixth month, and 
then grows more slowly at a uniform rate until birth. 
