454 
HALBERT L. DUNN 
The relation of the spinal cord volume to the volume of the 
entire brain is shown in figure 22 and in table 40. At the middle 
of the second month the cord volume is equal to 4.4 per cent of 
the total brain volume. 
It then drops rapidly at first and 
afterward more slowly to about 0.85 per cent of the total brain 
volume at birth. 
TABLE 31 
Frontospinal length 
Formula: Frontospinal length (em.) = (2 crown-heel length (em.))47 — 2.2 
(145 cases) 
embrace ieeancrs’ “ (ueleawaien eee eee 
FRONTOSPINAL | OBSERVED AND Aten nae 
Maxi- Mini- LENGTH CALCULATED 
Range Mean eat tah Mean MEANS 
cm. cm. cm. cm. Luts cm. cm. 
Oto 5 AON AKO 0.7 0.9 0.5 —0.5 3 
5 to 10 618 |. 1.7 1.0 1.4 1.2 =e 9 
10 told 2. | 2.9 1.9 2.1 23 ae 20 
15 to 20 | 16.6] 3.5 2.6 DG 3.0 eet 14 
20.46: 251\ 22.6.) “4.5 3.0 3.8 3.8 0 20 
25 to 30 | 27.0| 4.6 3.4 4.1 4.3 0), 2 15 
30 to 35 | 32.8 | 5.3 4.3 4.8 4.9 +0.1 rely; 
35 to 40 | 37.1 | 6.5 4.0 5.3 5.4 220.2 19 
40 to 45 | 42.2| 6.8 5.1 5.9 5.8 Sail 12 
45 to 50 | 48.2] 6.9 5.9 6.3 6.4 eet 8 
50 to 55 | 52.2| 7.3 6.3 6.8 6.7 =n 8 
TABLE 32 
Calculated frontospinal length at 5-cm. intervals of crown-heel length 
CROWN-HEEL LENGTH 
CALCULATED FRONTO- | 
SPINAL LENGTH | 
INCREMENT IN EACH 
5-CM. INTERV! 
AL 
cm. 
0.75 
1.89 
2.75 
3.46 
4.09 
4.65 
Dold 
5.64 
6.09 
6.51 
6.91 
cm. per cent 
1.14 152.0 
0.86 44.8 
0.71 28.2 
0.63 18.2 
9.56 13.4 
0.52 12.4 
0.47 9.3 
0.45 8.0 
0.42 6.7 
0.40 6.3 
RATIO TO NEW-BORN 
per cent 
11.5 
29.0 
42.2 
53.1 
62.8 
71.4 
79.5 
86.6 
94.5 
100.0 
106.2 
