444 Chapter XIV 



esting is that made by Escherich. In an infant examined for the 

 first time whilst it was still in good health, the blood was incapable 

 of protecting the guinea-pig. Some time after this negative result 

 had been obtained the child was attacked by a mild diphtheria, which 

 gave rise to the development of antitoxin, for its blood when again 

 examined exhibited a very high antitoxic power. This proves most 

 clearly that even a slight attack of diphtheria is capable of producing 

 antitoxic power in the body fluids. This observation may be utilised 

 to explain the frequency of the presence of this property in the blood 

 of persons in good health who, according to their own statements, 

 have never had diphtheria. This fact has been established by the 

 researches of A. Wassermann 1 , Abel (l.c.), and Orlowski. According 

 to the last observer, the blood in one-half the children in the hospital 

 at Gratz who had not been attacked with diphtheria was antitoxic 

 against the diphtheria toxin, sometimes even to a higher degree 

 than was that of the children who had recovered from this disease. 

 Wassermann has demonstrated that in adults this antidiphtheritic 

 power of the blood is even more frequent than in children, and that it 

 increases with age. Nevertheless, these persons affirm that they have 

 never had an attack of the disease. To explain this very paradoxical 

 fact, Wassermanu asked himself whether the individuals whose blood 

 was antidiphtheritic did not owe this property to the action of 

 pseudo-diphtheria bacilli. Although incapable of causing the disease, 

 these bacilli might, perhaps, exert a certain immunising influence 

 and give rise to the production of an antitoxin active against true 

 diphtheria toxin. Researches, directed to the clearing up of this 

 point, have not led Wassermann to reaffirm his suggestion. It must 

 be observed that the varieties of these pseudo-diphtheria bacilli are 

 [466] numerous, and that some of them, perhaps, may be capable of fulfilling 

 the function suggested by Wassermann. On the other hand, it is 

 proved that the specific and virulent diphtheria bacillus may be 

 found in the throat of persons in good health either without inducing 

 diphtheria, or only giving rise to a very slight form of disease of very 

 short duration. We must bear in mind that in persons who have 

 not had typhoid fever, but who live among patients suffering from 

 this disease, the blood may be very agglutinative (Foerster) ; that in 

 others, unattacked by cholera but containing Koch's vibrios in the 

 intestine, the blood may acquire a high specific protective power 

 (Sobernheim). It is probable that the same rule applies also to the 

 1 Ztschr.f. Hyg., Leipzig, 1895, Bd. xix, S. 403. 



