550 BACTERIOLOGY. 



To those ill-defined substances whose affinities are 

 restricted to the soluble toxins elaborated by the inva- 

 ding bacteria the name " antitoxins " is now generally 

 applied. Contrary to what we have seen in the case of 

 the germicidal substances, normally present in the blood, 

 antitoxins are to be detected in the normal animal 

 organism in very small amounts. When they do exist 

 under such conditions they are of but comparatively 

 feeble potency. 1 In the great majority of instances 

 antitoxic activities are acquired peculiarities ; acquired 

 in some cases in a more or less natural manner, as in 

 the course of a non-fatal attack of a specific malady ; 

 induced in others by purely artificial means, as we have 

 seen to be possible in the case of diphtheria, tetanus, 

 etc. Our acquaintance with these bodies extends little 

 further than their physiological functions and some of 

 the means that induce their generation. We have no 

 satisfactory knowledge of their intimate nature or of the 

 primary sources of their production. They are believed 

 by some (Buchner 2 and Metchnikoff 3 ) to represent, 

 when artifically induced, bacterial toxins that have been 

 modified by the vital action of the integral cells of the 

 body; and Roux 4 and Buchner 5 maintain that they 

 exhibit their protective functions less by direct combina- 



1 See Bolton : Transactions of Association of American Physicians, 

 1896, vol. xi. p. 62. Pfeiffer : Deutsche med. Wochenschrift, 1896, 

 No. 8. Fischl and v. Wunschheim: Centralblatt fiir Bakteriologie, 

 Parasitenkunde, und Infektionskrankheiten, 1896, Abt. i. Bd. xix. S. 

 652. Wassermann : Berliner klin. Wochenschrift, 1898, No. 1. 



2 Buchner: Miinchener med. Wochenschrift, 1893, Nos. 24 and 25. 



3 Metschnikoff: Weil's Handbuch der Hygiene, Bd. ix. Lieferung 1, 

 S. 48. 



*Roux : Annales de 1'Institut Pasteur, 1894, p. 722. 



6 Buchner: Berliner klin. Wochenschrift, 1894, No. 4. 



