110 BIOLOGY OF DEATH 



it is not possible to go behind such returns biologically. 



The second line of Table 8, "Ill-defined diseases, " 

 furnishes a striking commentary on the relative efficiency 

 of the medical profession in the United States and Eng- 

 land in respect of the reporting of the causes of death. 

 Only about one-fourth as many deaths appear in the 

 English vital statistics as due to ill-defined and unknown 

 causes as in the United States figures. 



Returning now to the consideration of the general 

 results set forth in Table 7 and Figure 26, a number of 

 interesting points about human mortality are apparent. 

 In the United States, during the decade covered, more 

 deaths resulted from the breakdown of the respiratory 

 system than from the failure of any other organ system 

 of the body. The same thing is true of England and 

 Wales. In Sao Paulo the alimentary tract takes first 

 position, with the respiratory system a rather close 

 second. The tremendous death rate in Sao Paulo charge- 

 able to the alimentary tract is chiefly due to the relatively 

 enormous number of deaths of infants under two from 

 diarrhoea and enteritis. Nothing approaching such a 

 rate for this category as Sao Paulo shows is known in 

 this country or England. 



In all three localities studied the respiratory and the 

 alimentary tract together account for rather more than 

 half of all the deaths biologically classifiable. These are 

 the two organ systems which, while physically internal, 

 come in contact directly at their surfaces with environ- 

 mental entities (water, food, air) with all their bacterial 

 contamination. The only other organ system directly 

 exposed to the environment is the skin. The alimentary 

 canal and the lungs are, of course, in effect invaginated 

 surfaces of the body. The mucous membranes which 

 line them are far less resistant to environmental stresses, 



