No. 630] 



TIU2IAX MORTALITY BATES 



43 



health and sanitation than Sao Paulo. This fact is re- 

 flected with perfect precision and justice in the relative 

 proportion of the death rates from endoderm and ecto- 

 derm. In the United States and England about 55 per 

 cent, of the classifiable deaths are chargeable to endo- 

 derm and about 9 to 14.5 per cent, to ectoderm. In Sao 

 Paulo 62.6 per cent, fall with the endoderm, and but 6.3 

 to 8.4 per cent, with the ectoderm. Since, as we have 

 already shown, public health measures can and do affect 

 practically only the death rate chargeable to endoderm 

 this result which is actually obtained is precisely that 

 which would be expected. 



Finally, it seems to me that the results of this study 

 add one more link to the already strong chain of evidence 

 which indicates the highly important part played by in- 

 nate constitutional biological factors as contrasted with 

 environmental factors in the determination of the ob- 

 served rates of human mortality. Here we have grouped 

 human mortality into broad classes which rest upon a 

 strictly biological basis. When this is done it is found 

 that the proportionate subdivision of the mortality is 

 strikingly similar in such widely dissimilar environments 

 as the United States, England and Southern Brazil. It 

 is inconceivable that such congruent results would ap- 

 pear if the environment were the predominant factor in 

 human mortality. This conclusion does not overlook the 

 fact that in some diseases the environment, in a broad 

 sense, is unquestionably the factor of greatest impor- 

 tance. Nor does it imply that every effort should not be 

 used to measure in every case the precise relative influ- 

 ence of constitution or heredity as compared with en- 

 vironment in the natural history of particular diseases. 

 This constitutes one of the most pressing and difficult 

 problems of medical science. 



