ANAPHYLACTOGENS, OR ALLERGENS 547 



sitization and intoxication do not occur. Guinea-pigs have, however, 

 been sensitized by feeding them meat or serum, and instances of buck- 

 wheat, fish, and egg idiosyncrasies would tend to indicate that intoxica- 

 tion may result from the ingestion of these substances in sensitive 

 persons. 



Rosenau and Amos 1 have demonstrated that proteins in a volatile 

 state, as in the exhaled breath of men, when condensed and injected into 

 guinea-pigs will sensitize these animals to subsequent injections of human 

 serum. While it is doubtful if the complex molecule possesses the power 

 of passing into the air in a gaseous form, it may probably exist in col- 

 loidal solution. Rosenau was also able, by keeping guinea-pigs hi 

 stables together with horses, to sensitize them to horse serum. These 

 experiments are of fundamental importance in explaining instances of 

 human anaphylactic phenomena among those sensitive to horse protein, 

 as, e. g., persons seized with sneezing and asthma when they come 

 near horses, and also tend to show how minute may be the quantity 

 of protein capable of sensitizing and intoxicating body-cells. 



Bacterial Anaphylactogens. All bacterial proteins are anaphy- 

 lactogens, although, on account of the physical state of the bacteria, 

 they yield reactions more irregular and weaker than those observed 

 with proteins in solution. The tuberculin, luetin, mallein, and similar 

 reactions are true anaphylactic phenomena. Rosenau and Anderson, 

 Vaughan and Wheeler, Kraus, and others have observed anaphylactic 

 reactions with various bacteria, such as Bacillus subtilis and colon, 

 typhoid, anthrax, and tubercle bacilli. Not infrequently reactions 

 occur during the therapeutic administration of tuberculin and bacterial 

 vaccines. 



This brings up the interesting question as to whether toxins are 

 anaphylactogens, a subject previously mentioned in the historic review 

 of this subject. Instances of hypersensitiveness to diphtheria and te- 

 tanus toxins were early observed in attempts to immunize horses in the 

 production of antitoxins. As it is extremely difficult, if not impossible, 

 to isolate a toxin free from other constituents of the medium into which 

 it was excreted by microorganisms, this question cannot be answered 

 in a definite manner. There is no direct proof, however, that toxins 

 sensitize, although the protein in the toxin filtrate may serve to do so. 

 In 1902 Vaughan and Gelston 2 showed that the poison contained in the 

 cellular substance of the diphtheria bacillus is an entirely different one 



1 Jour. Med. Research, 1911, xxv, 35. 



2 Trans. Assoc. Amer. Phys., 1902, 17, 308. 



