594 
STATISTICS: R. PEARL 
It should be emphasized that the underlying idea of this rearrangement 
of the causes of death is to put all those lethal entities together which 
bring about death because of the functional organic breakdown of the 
same general organ system. The cause of this functional breakdown 
may be anything whatever in the range of pathology. It may be due to 
bacterial infection; it may be due to trophic disturbances; it may be due 
to mechanical disturbances which prevent the continuation of normal 
function; or to any other cause whatsoever. In other words, the basis 
of the present classification is not that of pathological causation, but it 
is rather that of organological breakdown. We are now looking at the 
TABLE 1 
Showing the Relative Importance of Different Organ Systems in Human 
Mortality 
GROUP 
NUMBER 
ORGAN SYSTEM 
DEATH RATES PER 100,000 
Registra 
U.S 
1906-10 
uion area, 
).A. 
1901-05 
England 
and Wales, 
1914 
Sao Paulo, 
1917 
II 
VI 
I 
VII 
IV 
III 
V 
VIII 
IX 
Alimentary tract and associated organs... . 
Circulatory system, blood 
Kidneys and related excretory organs 
Primary and secondary sex organs 
Skeletal and muscular system 
Skin 
395.7 
334.9 
209.8 
175.6 
107.2 
88.1 
12.6 
10.1 
1.5 
460.5 
340.4 
196.8 
192.9 
107.4 
77.4 
13.7 
13.3 
1.2 
420.2 
274.1 
208.6 
151.9 
19.4 
95.4 
18.2 
12.0 
1.9 
417.5 
613.8 
254.8 • 
124.3 
83.4 
103.2 
6.8 
7.9 
1.1 
Endocrinal system 
Total death rate classifiable on a biological 
1335.5 
1403.6 
1231.7 
1612.8 
X 
171.3 
211.9 
141.4 
109.8 
question of death from the standpoint of the pure biologist, who concerns 
himself not with what causes a cessation of function, but rather with 
what part of the organism ceases of function, and therefore causes death. 
2. In table 1 the death rates per 100,000 are arranged in descending 
order of importance (for the United States Registration Area 1906-10) 
by organ systems. Four sets of data are used: (a) the United States 
Registration Area for the five years, 1906-10 inclusive; (b) the same, 
1901-05; (c) England and Wales, 1914; and (d) Sao Paulo, Brazil, 1917. 
3. The data show that in the United States, during the decade covered, 
more deaths resulted from the breakdown of the respiratory system than 
irom the failure of any other organ system of the body. The same thing 
