8 ANAPHYLAXIS AND ANTI-ANAPHYLAXIS 



The observations recorded by v. Pirquet and 

 Schick relating to the hypersensitiveness of the 

 human subject in the presence of serum were pub- 

 Hshed in the same year (1903), and were mainly 

 clinical. In a short note preceding their account 

 these authors sought to bring into relief the fact that 

 the body, when treated with certain substances — 

 serum in particular — acquired the power of reacting 

 more rapidly to a reinjection of the same substance. 



Having had under observation a large number of 

 children treated with sera — antidiphtheritic and anti- 

 scarlatinal — these authors described under the name 

 of " serum sickness " a variety of symptoms following 

 this treatment. The}^ remarked that in children who 

 had received this serum for the first time serum 

 complications appeared after seven to twelve days 

 from the time of incubation, never before six days. 

 On the other hand, in children who were injected 

 with serum for the second time the incubation period 

 was distinctly shortened; the serum sickness might 

 even make its appearance immediately after the in- 

 jection, or at the latest some hours afterwards, and 

 that with quite weak doses of serum (i c.c). 



Therefore the first dose sensitised the child : after 

 a second injection serum complications appeared with 

 greater rapidity and regularity; more than this, they 

 appeared as a sequel to a weaker dose of serum than 

 was injected on the first occasion. 



The study of serum anaphylaxis only entered upon 

 its fruitful stage from the experimental point of view 

 when the guinea-pig was adopted ai^^the most suitable 

 animal for the experiments. 



In American laboratories for serum therapy this 

 curious fact had long ago been observed — namely, 

 that guinea-pigs which had been employed for the 

 testing of antidiphtheritic serum exhibited as a 



