444 HALBERT L. DUNN 
form only about 2.7 per cent, and from that time on to birth they 
gradually decrease in relative volume, so that they form only 
1.5 per cent of the entire brain volume in the new-born. This 
0 5 10 15 £0 (ay 350 35 40 AD 50 55cm. 
Fig.14 Field graph and curve of the growth of the pons and medulla in weight 
and volume in fetal life. Abscissa: total body length in cm. Ordinate: pons 
and medulla 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 [(0.2X)2-57 + 20.0]. (Data from tables 23 and 24.) 
relative decline is clearly due to the great increase in the ab- 
solute volume of the cerebral hemispheres and of the cerebellum 
during the last half of fetal life. 
