ANAPHYLAXIS 383 



ference of anaphylaxis or with active sensitization due to traces of 

 antigen carried over with the serum of the sensitive animal. For 

 the purposes of theoretical deduction, therefore, it is better to ignore 

 these cases and consider chiefly passive transference in which reac- 

 tions are obtained within 24 hours or less after the injection of the 

 anaphylactic serum an interval so short that active sensitization 

 can hardly be considered as a reasonable possibility. 



The important point, in this connection, is the fact that it was 

 found that between the administration of sensitive serum and of 

 antigen a definite interval, however short, was invariably necessary. 81 



From these observations the natural deduction was made that the 

 anaphylactic symptoms were the result of cellular occurrences, and 

 that the antigen could act only after the sensitizing substance (how- 

 ever conceived) had become attached to certain cells, .probably to 

 those of the central nervous system. It was thought that a meeting 

 of antigen and the sensitized body in the circulation would result in 

 no reaction; that, in other words, the effective reaction was not a 

 direct, but an indirect, one after the anaphylactic "antibody" of the 

 sensitive serum had become bound to the cells. It will be neces- 

 sary to recur to this problem when we discuss the various theories 

 of anaphylaxis, where we will see that this point has been one of the 

 crucial ones in the controversy between the two main directions of 

 thought on anaphylaxis. 



81 An exception to this, contradicting the then prevailing opinion, were 

 the researches of Weill-Halle and Lamaire (C. E. de la Soc. de Biol., Vol. 

 65, July, 1908, p. 141), who showed that, under certain conditions, guinea 

 pigs would react with typical, often fatal, anaphylaxis if injected simul- 

 taneously with the serum of sensitized rabbits and the antigen horse serum. 

 According to them, the success of such experiments depended entirely upon 

 the condition of the sensitive serum that is, the time at which the rabbits 

 treated with horse serum were bled. These experiments, we shall see, were 

 later confirmed. We record them, though important, in a footnote, since we 

 wish at present to emphasize the reasoning which led to the assumption of a 

 cellular participation in the reaction. 



