452 HALBERT L. DUNN 
a fairly rapid rate of absolute growth from the third to the be- 
ginning of the fifth month and a slower and more regular growth 
thereafter. 
The data of Jackson (’09) (table 35) show a uniformly higher 
average for the absolute spinal cord volumes. His small fetuses 
TABLE 29 
Length of the colliculi 
Formula: Colliculi length (em.) = .015 crown-heel length (cm.) + .47. 
(117 cases) 
E D 
CROWN-HEEL LENGTH CAEL NAGLE) DSU DIFFERENCE 
eee) penne on || emer aire | SE 
Rene Minie THE COLLICULI | CALCULATED 
Range Mean main Tali Mean MEANS 
cm. cm. cm. cm. cm. cm. cm. 
Oto 5 
5 to 10 
10 to 15 | 13.0 0.9 0.5 0.66 0.66 0 11 
15 to 20 | 16.9 0.9 0.5 0.74 0.73 —0.01 14 
205025) 92255 1.0 0.7 0.80 0.81 +0.01 18 
25 to 30 | 26.9 1.0 0.7 0.90 0.87 —0.03 12 
30 to 35 | 32.8 1.7 0.8 0.99 0.96 —0.03 16 
35 to 40 | 37.1 ileal 0.9 0.98 1.03 +0.05 18 
40 to 45 | 42.2 1.2 1.0 1.10 1.10 0 12 
45 to 50 | 48.3 1.4 ileal 1.23 20 —0.03 8 
50 to 55 | 5252 1.3 Weal 1.20 1.25 +0.05 8 
TABLE 30 
Calculated length of the colliculi at 5-cm. intervals of crown-heel length 
INCREMENT IN EACH 
CROWN-HEEL LENGTH LENGTH OF COLLICULI 5-OM. INTERVAL 
RATIO TO NEW-BORN 
cm. cm. em. per cent per cent 
5 
10 
15 0.695 57.0 
20 0.775 0.75 10.8 63.1 
25 0.845 0.75 9.8 69.3 
30 0.920 0.75 8.9 75.4 
35 0.995 0.75 8.2 81.5 
40 1.070 0.75 7.6 87.8 
45 1.145 0.75 7.0 93.9 
50 1.220 0.75 6.6 100.0 
55 1.295 0.75 6.2 106.2 
