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THE AMERICAN NATURALIST [Vol. LIV 



those under the general heading IV, "Diseases of the 

 respiratory system" of the International Classification, 

 with a single exception, namely No. 88, "Diseases of the 

 thyroid body," which goes elsewhere in the present clas- 

 sification. In addition, there are in Table II four causes 

 of death which are not included with the respiratory 

 system in the International List. These four we may 

 consider in detail. 



Item 28, "Tuberculosis of lungs," obviously belongs 

 with the respiratory system, in a strictly organological 

 classification. The breakdown of the lungs as a function- 

 ing system is the biological meaning of death from pul- 

 monary tuberculosis. This item is taken from rubric I, 

 "General diseases," of the International Classification. 

 Acute miliary tuberculosis has been included with pul- 

 monary tuberculosis here, rather than as a separate item, 

 for the reason that the English statistics treat these 

 items together. No significant error is introduced by 

 this procedure for two reasons : (a) the rate from miliary 

 tuberculosis by itself is very small; and (b) probably a 

 majority of cases of acute miliary tuberculosis have the 

 lungs as the chief organ affected. 



Item 9, "Diphtheria and croup," is again obviously a 

 respiratory category, on the basis of organs affected. It 

 does not seem to me to be to the point to argue that death 

 in diphtheria is in many cases due to a general toxemia. 

 To do so brings into prominence an aspect of the matter 

 foreign to our present point of view. The infecting 

 agent attacks a part of the respiratory system. If that 

 system were in man as in the insects, lined with chitin in 

 considerable part, presumably death from the clinical 

 entity known as diphtheria would never occur, because 

 the organism would not get the necessary foothold to 

 produce enough toxin to be troublesome. It seems to me 

 further that there is a fundamental biological difference 

 between the cases of scarlet fever and septicemia on the 

 one hand, and diphtheria on the other hand, which leads 

 to the placing of the former with the blood and the latter 



