SENSITISING INJECTION 19 



to 1 00° C. and even to 120° C. without effecting a 

 disappearance of the sensitising power. 



The result of experiments which we have carried out 

 along these lines shews that the sensitising property 

 of serum is of a heat-resisting character.^ This fact 

 was at first disputed by some authors. In fact, since 

 our experiments were undertaken several papers have 

 been published in which different conclusions are 

 drawn. Rosenau and Anderson,^ for instance, have 

 stated that sensibiligen entirely disappears from 

 serum heated to 100° C. Doerr and Russ^ affirm that 

 it is impossible to sensitise with serum even when 

 heated to 80^ C. On the other hand, Kraus and 

 Volk* succeeded in sensitising with serum heated to 

 90° C. Arthus* has likewise confirmed our results by 

 showing that rabbits can be sensitised with serum 

 heated to 100° C. 



It was not without interest, therefore, that we 

 examined the reason for these contradictory state- 

 ments; especially as it was of importance to dispel 

 all idea of a possible error on the part of the experi- 

 menters. 



It did not take long to convince us that there was, 

 in fact, no question of any error having been made. 

 If the authors had been unable to agree, it was because 

 they were working with sera of different dilutions. 

 In fact, it follows from our experiments that the 

 sensitising property (just as is the case, as we shall 

 see later, with the vaccine and the toxin) is depen- 

 dent on the physical state of the serum. The more 

 the serum is diluted the less is it coagulated by heat, 

 and the less is its sensitising property affected. In 



1 Comptes tend. Soc. de Biol., 1907, Ixiii., p. 294. 



2 Journal of Medical Research, 1908, xix., p. 37. 



3 Zeitschrift f. Immunitatsforschung, I. Orig., 1909, p. 109. 

 « Ibid., 1909, p. 731, 



' Arch. Internat. de Physiol., 1909, vii,, p. 471. 



