THE CAUSATION OF DISEASE. l6l 



variously modify them in the person affected, but seem to me 

 utterly inadequate to originate them." 



Although more recent evidence tends to negative this con- 

 clusion (for gout may perhaps be induced independently of 

 heredity — more especially if the individual come under the 

 influence of lead in addition to other gout-producing agents — 

 and tuberculosis has been inoculated in a large number 

 of animals), nevertheless, this conclusion emphasizes Paget's 

 belief, which is surely correct, that the special tendency to the 

 disorders in question is gradually evolved, and that without 

 such tendency, such peculiarity of S, they are never met with 

 under any ordinary circumstances. 



The same line of argument might be pursued in respect, of 

 all sorts of disease. Can we even guarantee to infect every child 

 with a given specific fever ? Are there not some children, who, 

 although they continually consort with others suffering from a 

 specific febrile disorder — nay, who, although they be even 

 inoculated with the virus thereof, will yet remain untouched by 

 the disease ? This inability of the S to be morbidly affected by 

 a specific virus is well shown in the case of individuals who 

 have already been thus morbidly affected. Such, we know, are 

 generally protected against future attacks of the disease, but 

 some are from the beginning proof against the poison ; and 

 in this connection it is interesting to remember that some 

 races are proof against specific E's, which to others are highly 

 injurious. 



Instance the ague poison. And this disparity of different 

 individuals in the matter of responding morbidly or other- 

 wise to parasitic organisms, does not apply to the micro- 

 scopic parasites only ; it is a curious fact that different 

 races of men differ in their liability to be attacked by the 

 several macroscopic parasites. tt The surgeon of a whaling 

 ship in the Pacific assured me that when the pediculi, with 

 which some Sandwich Islanders on board swarmed, strayed on 

 to the bodies of some English sailors, they died in the course of 

 three to four days."* Humboldt remarks : " White men, born 

 in the torrid zone, walk barefoot with impunity in the same 



* " Variation under Domestication," vol. ii. p. 265. 



