596 
STATISTICS: R. PEARL 
due, in the case of England, to two factors, premature birth and cancer. 
In Sao Paulo it is due to premature birth and syphilis. 
In a broad sense the efforts of public health and hygiene have been 
directed against the affections comprised in the first two items in the 
table, respiratory system and ahmentary tract. The figures in the first 
two columns for the two five year periods in the United States indicate 
roughly the rate of progress such measures are making, looking at the 
matter from a broad biological standpoint. In reference to the respi- 
TABLE 2 
Showing the Relative Influence of the Primary Germ Layers in Human 
Mortality 
(Items 64 and 65 charged to ectoderm) 
LOCALITV 
DEATH RATE PER 100,000 DUE TO FUNCTIONAL BREAKDOWN 
Of ORGANS EMBRYOLOGICALLY DEVELOPING PROM 
Ectoderm 
Per cent 
Meso- 
derm 
Per cent 
Endo- 
derm 
Per cent 
United States Registration Area,1906-10 
191.1 
14.3 
425.2 
31.8 
719.6 
53.9 
United States Registration Area,1901-05 
210.6 
15.0 
407.1 
29.0 
786.2 
56.0 
England and Wales, 1914 
177.1 
14.4 
374.0 
30.3 
681.5 
55.3 
Sao Paulo, 1917 
134.9 
8.4 
468.0 
29.0 
1009.9 
62.6 
TABLE 3 
Showing the Relative Influence of the Primary Germ Layers in Human 
Mortality 
(Items 64 and 65 charged to mesoderm) 
LOCALITY 
DEATH RATE PER 100,000 DUE TO FUNCTIONAL BREAKDOWN 
OF ORGANS EMBRYOLOGICALLY DEVELOPING FROM 
Ectoderm 
Per cent 
Meso' 
derm 
Per cent 
Endo- 
derm 
Per cent 
United States Registration Area, 1906-10 
116.9 
8.7 
499.4 
37.4 
719.6 
53.9 
United States Registration Area, 1901-05 
137.3 
9.8 
480.4 
34.2 
786.2 
56.0 
England and Wales, 1914 
107.9 
6.7 
443.2 
36.0 
681.5 
55.3 
Sao Paulo, 1917 
101.3 
6.3 
501.6 
31.1 
1009.9 
62.6 
ratory system there was a decline of 14% in the death rate between the 
two periods. This is substantial. It is practically all accounted for in 
phthisis, lobar pneumonia, and bronchitis. For the alimentary tract 
the case is not so good — ^indeed, far worse. Between the two periods 
the death rate from this cause group fell only 1.8%. 
4. The next step in the investigation was to arrange all the organo- 
logically classifiable death rates under the primary germ layers (ectoderm, 
mesoderm, and endoderm) from which the organs concerned developed 
embryologically. The results are set forth in tables 2 and 3, and in 
