398 INFECTION AND RESISTANCE 



tant studies on the mechanism of anaphylaxis in rabbits. He found 

 that passive sensitization in these animals, in contrast to the work of 

 others upon guinea pigs, was best obtained by the simultaneous in- 

 travenous injection of antigen and anaphy lactic serum. If the injec- 

 tion of the sensitive serum preceded that of the antigen by as much 

 as 24 hours, the reaction became indistinct (undeutlich), and Friede- 

 mann concluded that here, at least, there could not be assumed the 

 necessity of preliminary sensitization of the body cells by the anaphy- 

 lactic serum, as is the case of guinea pig anaphylaxis. The anaphy- 

 lactic poison, whatever it may be, Friedemann concludes is, in rabbits 

 at least, formed in the circulating blood. In 1910 Biedl and Kraus 42 

 obtained immediate and severe symptoms in guinea pigs when they 

 injected intravenously mixtures of horse serum together with the 

 serum of sensitized guinea pigs. Briot 43 in the same year obtained 

 reactions in young rabbits into which he had injected mixtures of 

 horse serum and anti-horse serum. Gurd 44 in a recent publication 

 obtained reactions in guinea pigs when he injected intravenously 

 immune rabbit serum (anti-sheep serum) and immediately thereafter 

 sheep serum. We ourselves have been able to obtain occasional and 

 distinct results in rabbits and guinea pigs both by simultaneous and 

 immediately consecutive intravenous injections of antigen and anti- 

 body, though we did not succeed in attempts to duplicate exactly the 

 experiments of Friedemann and of Biedl and Kraus. 



Recently too Manwaring and his co-workers studying the isolated 

 hearts of rabbits, and the isolated lungs of guinea pigs, by physio- 

 logical methods, have claimed that they can observe reactions due to 

 the meeting of antigen and antibody in the blood vessels. 



There is thus a considerable amount of evidence that in rabbits, 

 and some other animals, the meeting of antigen and antibody in the 

 blood stream may lead to anaphylactic reaction. However, the evi- 

 dence in guinea pigs that this may occur is very slim, and to any one 

 who has worked in anaphylaxis consistently it is quite plain that in 

 these animals the simultaneous injection of the two substances leads to 

 either no symptoms, or such very slight ones that they play no im- 

 portant part in the fatal reaction. Even in other animals, further- 

 more, we ourselves feel that mere contact within the blood stream be- 

 tween antigen and antibody cannot account for the entire train of 

 phenomena, and one is forced to assume that any considerable degree 

 of hypersusceptibility must be essentially cellular and due to the 

 reaction of injected antigen with antibody that has previously be- 

 come attached in some way to tissue cells. 



The idea in itself is not new. Wassermann had first suggested it in 

 an attempt to explain the peculiar hypersusceptibility to toxin pos- 



42 Biedl and Kraus. Ztschr. f. Immunitatsforsch., 1910, iv. 



43 Briot. Compt. rend. Soc. de biol, 1910. Ixviii, 402. 



44 Gurd. Jour. Med. Besearch, 1914, xxxi, 205. 



