462 .  HALBERT L. DUNN 
seventh fetal month and from that time until birth it exceeds all 
other growth activity in the central nervous system. The last 
type, compound growth, represents merely the combined effect 
of two or more of the above types predominated by the mass of 
the cerebral hemispheres. ‘These varieties of growth will now be 
considered in more detail. 
TABLE 38 
Combined brain-cord length 
Formula: Brain-cord length (em.) = (10 crown-heel length (cm.))-*!4 —4 
(137 cases) 
BRAIN-CORD | OBSERVED AND On ORaEE 
Mee Me LENGTH CALCULATED 
Range Mean muni mum Mean MEANS 
cm. cm. cm. cm. cm. cm. cm. 
OMORS 4.0 4.9 Sea woe O Dall —=O(023 3 
5 to 10 Tall On 4.0 4.4 4.9 +0.5 G 
10 to 15 12:1 8.5 5.0 6.9 7.8 +0.9 20 
15 to 20 16.6 Woh eo 9.8 9.8 0 14 
20 to 25 22.6 14.7 LORZ Ze. 12.2 0), 19 
25 to 30 26.9 Mayall 12.1 13.8 13.8 0 13 
30 to 35 32.8 18.4 14.1 15.4 15.6 — (52 16 
35 to 40 37.1 20.2 13.5 17.4 16.9 =(0).5) 17 
40 to 45 42.2 ORs 16.1 18.1 18.4 —0.3 11 
45 to 50 ASeD | 217 18.8 19.8 19.9 +0.1 9 
50 to 55 92.2 23.1 20.4 | 21.3 20.9 —0.4 8 
TABLE 39 
Calculated combined brain-cord length at 5-cm. intervals of crown-heel length 
INCREMENT IN EACH 
= v y. D 
CROW N-HEEL LENGTH BRAIN-CORD LENGTH 5-CM. INTERVAL 
RATIO TO NEW-BORN 
cm. cm. em. per cent per cent 
5) 3.5 17.2 
10 6.6 3.1 88.5 32.3 
15 9.2 2.6 39.4 . 45.1 
20 11.2 2.0 74 NY 6 54.9 
25 13.1 1.9 17.0 64.2 
30 14.8 Lid, 13.0 72.5 
35 16.3 1.5 10.1 79.9 
40 17.8 1.5 Or2 87.2 
45 19S 1.3 7.3 93.6 
50 20.4 1.3 6.4 100.0 
55 21.6 ie” 5.9 106.0 
