222 ANAPHYLAXIS 



The parenteral introduction of a foreign proteid into an or- 



Proteid ganism results in the formation of antibodies against this 



Anaphylaxis. proteid: precipitins, cytolysins, complement fixation bodies, 



etc. At first it was assumed that a "proteid immunity" had 

 taken place. Such conclusion proved erroneous. 



Richet and Portiers (1902) in working with actino-congestin (a substance extracted 

 from the tentacles of Actinia) demonstrated that dogs injected with sublethal doses of 

 this toxin would die acutely if the injection were repeated after an interval of three 

 weeks. In the light of more recently established facts, the explanation of Richet's 

 work was complicated because actino-congestin consists of two components, a true 

 toxin against which an immunity can be stimulated, united with a proteid element 

 which like all proteids produces anaphylaxis. 



It was therefore of extreme fundamental importance when Arthus and 

 Theobald Smith showed that proteid substances, of themselves apparently 

 non-toxic, can constantly produce the phenomena associated with hyper- 

 sensitiveness. 



The Arthus Phenomenon. 



If a rabbit is injected subcutaneously with horse's serum at intervals of 

 six days, a soft infiltrate which remains for two to three days appears at 

 the site of injection after the fourth inoculation, a harder infiltration which 

 continues for a longer period of time after the fifth inoculation, and gangrene 

 after the sixth or seventh. A rabbit repeatedly treated intravenously 

 with horse's serum may die with severe general symptoms several minutes 

 after one of the later inoculations. 



The Theobald Smith Phenomenon. 



Theobald Smith observed that guinea-pigs injected with neutral mix- 

 tures of diphtheria toxin and horse's antitoxic serum would be killed if 

 after an interval of several weeks they were given a subcutaneous injection 

 of normal horse's serum. 



Otto and others showed that both of these phenomena, above described, 

 are identical in their principle; thus, that of Arthus can be likewise in- 

 duced after a single injection of horse's serum if the first dose is small, and 

 if the interval between the first and second inoculation is sufficiently long 

 (about three weeks or more). 



Further study proved that anaphylaxis may be incited by repeated paren- 

 teral introduction of practically any foreign proteid. 



The first inoculation prepares the animal in such a manner that after a 

 definite incubation period the second injection of the same serum will 



