456 HALBERT L. DUNN 
DISCUSSION 
The discussion of the results of this work will be limited to, 
1) a comparison of the growth of the central nervous system as a 
whole with that of the various other viscera and parts of the body 
in the fetal period; 2) the analysis of the type of growth of the 
TABLE 33 
Volume of the spinal cord 
Formula: Spinal cord volume (ec.) = .01[(0.17 crown-heel length (em.) )?:57 + 11.] 
(128 cases) 
VOLUME OF | OBSERVED AND or CABES 
Maxi- Mini- SPINAL CORD CALCULATED 
Range Mean ain ae Mean MEANS 
cm. cm. ce. Ge. (HP: ce. ce. 
Oto 5 
5 to 10 fea OXO5n| 02 05m 0205 0.13 0.08 3 
10 to 15 1220" 7OF3 0.1 0.2 0.2 0 18 
15 to 20 1GRS 5) O25 0.1 0.3 0.3 0 14 
20 to 25 22.6 | 0.7 0.3 0.5 0.4 —0.1 19 
25 to 30 26.9 iil 0.3 0.65 0.6 0 14 
30 to 35 32.6 1.4 O25 0.9 0.9 0 17 
35 to 40 SHC) | 24a 0.7 15d ila 0 17 
40 to 45 41.9 2.3 52 ise led 0 11 
45 to 50 48.0 3.1 1.4 2.4 2.3 —(): 1 7 
50 to 55 52.2 3.8 1.8 2.5 2.8 +0.3 8 
TABLE 34 
Calculated spinal cord volume at 5-cm. intervals of crown-heel length 
INCREMENT IN EACH 
CROWN-HEEL LENGTH SPIN CORD 
RO H PINAL CORD VOLUME 5-CM. INTERVAL 
RATIO TO NEW-BORN 
cm. ce. ce. per cent per cent 
5 
10 0.15 5.9 
15 0.22 0.07 46.7 8.6 
20 0.34 0.12 - 64.5 13.3 
25 0.52 0.18 53.0 20.3 
30 O47 0.25 48.1 30.1 
30 1.09 0.32 41.5 42.5 
40 1.49 0.40 36.7 58.2 
45 1.98 0.49 32.9 77.4 
50 2.56 0.58 29.2 100.0 
55 3.24 0.68 24.5 126.5 
