418 HALBERT L. DUNN 
The rate of growth of the volume of the central nervous system 
as determined by the 5-cm. interval percentage increment 
(page 413), (fig. 26, curve I) is approximately 120 per cent for the 
10-to-15-cm. interval and descends gradually to about 40 per 
cent for the 50-to-55-cm. interval. 
TABLE 1 
Volume of the central nervous system 
Formula: Volume of the central nervous system (cc.) = [0.114 (crown-heel 
length em.)]3-34 + 2.0 
(146 cases) 
ORSERVED VOLUME OF 
CENTRAL NERVOUS SYSTEM 
DIFFERENCE 
BETWEEN 
OBSERVED AND 
CALCULATED 
CROWN-HEEL LENGTH CALCULATED 
VOLUME OF 
CENTRAL NER- 
VOUS SYSTEM 
NUMBER 
OF CASES 
Range Mean saan ats Mean MEANS 
cm. cm. cc. ce. cc. cc. cc. 
Oto 5 3.9 0.7 0.1 0.3 4 
5 to 10 ez 2.4 0.6 1.3 12 
10 to 15 12.2 8.6 2.1 5.4 5.0 —0.4 21 
15 to 20 16235) 2220 3.0 12.5 10.8 —1.7 16 
20 to 25 22.6} 49.5 17.4 ole 25.6 —5.5 19 
25 to 30 Patt Ak 65.4 | 24.7] 46.9 45 .3 —1.6 12 
30 to 35 382.8 | 144.2 | 45.8 | 81.8 83.9 +2.1 18 
35 to 40 37.2 | 222.8 | 102.2 | 141.4 126.7 —14.7 iff 
40 to 45 42.2 | 256.9 | 145.3 | 197.7 187.6 —10.1 12 
45 to 50 48.0 | 412.5 | 207.0 | 306.0 294.0 —12.0 7 
50 to 55 52.2 | 414.3 | 332.3 | 367.5 388 .5 +21.0 8 
TABLE 2 
Calculated volume of the central nervous system at 5-cm. intervals of crown-heel length 
VOLUME OF CENTRAL INCREMENT IN EACH 
CROWN-HEEL LENGTH 
NERVOUS SYSTEM 
5-cM. INTERVAL 
cc. 
4.4 
a 
17.3 
27.8 
40.7 
57.4 
76.4 
99.5 
125.4 
per cent 
122.0 
121.2 
97.6 
79.4 
65 .0 
50.4 
47.5 
41.9 
37.2 
RATIO TO NEW-BORN 
per cent 
