ANAPHYLACTIC ANTIBODY. 389 



antibody and the actual sensitization of the animal 

 varies with the different methods of injection. In 

 case of intraperitoneal injection this time is about 

 twenty-four hours; in intravenous injections it is 

 about one and one-half hours. 



Different means of measuring the sensitizing 

 strength of antiserums have been suggested. Doerr 

 and Euss injected decreasing quantities of the 

 serum into guinea-pigs and then by injecting 

 twenty-four hours later an intoxicating quantity 

 of antigen into each of these pigs, the amount of 

 antiserum necessary to produce sensitization was 

 found. A second method is to inject a definite 

 quantity of antiserum into each of a series of pigs 

 and then twenty-four hours later to inject decreas- 

 ing quantities of antigen to find the smallest 

 amount necessary to cause acute death. Doerr 

 and Euss suggest as a unit of anaphylaxis anti- 

 serum or of anaphylactin such a serum as will in 

 a dose of 1 c.c. intraperitoneally sensitize a 250 

 gm. guinea-pig so that acute death may be pro- 

 duced in twenty-four hours by injecting a sufficient 

 quantity of antigen. 



The close connection between anaphylactogen Relation to 

 and precipitinogen has already been alluded to. Antibodies. 

 In a similar way, anaphylactin and precipitin are 

 so closely allied that Friedberger, Doerr, and 

 others consider them identical. As objections to 

 this view it is pointed out that animals which do 

 not readily produce precipitins, such as guinea- 

 pigs and dogs, are most susceptible to sensitization ; 

 and secondly, that in the state of antianaphylaxis, 

 to be described later, precipitins may be present, 

 but apparently the anaphylactin is exhausted. 



