96 Immunity 



ferent chemical composition and physiological activity. 

 Some are toxalbumins, some are enzymes, some are 

 bacterio-proteids. The true nature of the greater number 

 of these bodies is unknown, but study of their physio- 

 logical action has brought forth the important fact that 

 their behavior toward the body cells is in no way different 

 from the behavior of the same cells toward other chemical 

 compounds of similar constitution, and that nearly all 

 physiologically active bodies introduced into living organisms 

 produce definite, though not necessarily visible, reactions. 



Some of the facts that bear upon immunity have long been 

 known though only recently correlated with it. Thus from 

 remote antiquity it has been known that those who regularly 

 consumed small quantities of poisons become irresponsive 

 to their action, and it is well known that Mithridates adopted 

 this mode of defending himself from his enemies. The im- 

 munity of opium and arsenic eaters, and the pleasurable 

 instead of poisonous effects of tobacco, are too well known 

 to require further mention. 



It was, however, only by beginning with the metabolic 

 products of bacteria, studying their activities, and comparing 

 them with other toxic and active substances that the present 

 state of knowledge has been attained. 



The work seems to have been begun by Chauveau,* who 

 believed that the immunity conferred by bacteria was due 

 to the presence of their soluble products, but the first direct 

 demonstration was given by Salmon and Smith, f who, as 

 early as 1886, showed that it was possible to immunize 

 pigeons against the hog-cholera bacillus by means of repeated 

 injection with cultures exposed to 60 C., and containing no 

 living organisms. CharrinJ found it possible to immunize 

 rabbits against Bacillus pyocyaneus by injecting them with 

 the filtered products of cultures of that organism, and 

 Bonome similarly to immunize animals against Bacillus 

 proteus, B. cholera gallinarum, and the pneumococcus. 

 Roux and Chamberland|| and Roux** were able by the use of 

 boiled cultures of the bacilli of malignant edema, and of 



* "Ann. del'Inst. Pasteur," 1888, 2. 

 f " Centralbl. f. Bakt.," etc., n, No. 18. 

 I " Compte rendu," cv, p. 756. 

 " Zeitschrift f. Hyg." v, p. 415. 

 || "Ann. del'Inst. Pasteur," 1887, 12. 

 ** Ibid., 1888, 2. 



