iO ANAPHYLAXIS AND ANTI-ANAPHYLAXIS 



Not one of the control animals that had received 

 at the time of the first injection the same dose of horse 

 serum (6 c.c.) became ill. Moreover, it was found 

 possible to inject them with a much larger dose with- 

 out giving rise to any ill-effects. 



In view of these findings Otto sought to inquire 

 whether the phenomenon that he had observed was 

 peculiar to horse serum, or whether it was manifested 

 in the presence of other kinds of serum. 



Experience soon shewed him that in the presence 

 of rabbit serum, goat serum, or ox serum, the guinea- 

 pigs that had been inoculated with antidiphtheritic 

 serum — that is to say, horse serum — behaved like 

 fresh guinea-pigs. In other words, those guinea-pigs 

 which had been originally injected with the toxin and 

 horse serum were only sensitised to horse serum; and, 

 on the other hand, remained indifferent to reinjection 

 of serum when that serum was derived from an animal 

 other than the horse. 



The question now remained, What was this sub- 

 stance which in the mixture as originally injected 

 communicated this state of hypersensitiveness to the 

 guinea-pig; was it the diphtheria toxin or the anti- 

 toxin {i.e., the horse serum)? 



With this purpose in view, a certain number of the 

 guinea-pigs were injected with diphtheria toxin; 

 four to twelve weeks later they were injected with 

 horse serum. The guinea-pigs thus treated did not 

 exhibit any noteworthy reaction; therefore the toxin 

 had nothing to do with the appearance of the pheno- 

 menon. 



This fact having been established, another series of 

 guinea-pigs was injected with variable doses of anti- 

 diphtheritic (horse) serum only, not mixed with toxin; 

 four to twelve weeks later the guinea-pigs were tested 

 with 6 c.c. of horse serum by subcutaneous injection. 

 None of the guinea-pigs died. A certain number of 



