386 INFECTION AND RESISTANCE 



Southard. 1 These workers are emphatic in denying that anaphylaxis 

 has the nature of an antigen-antibody reaction. Their views are 

 summarized in the following as nearly as is feasible in their own 

 words : 



Increased susceptibility in the sensitized animal is due to the 

 continued presence in the circulation of an unneutralized element of 

 the antigen (in their case horse serum), which they call "anaphy- 

 lactin," which acts as an irritant or stimulant to the body cells, and, 

 in some way, causes them to assimilate over rapidly certain other 

 elements of horse serum. These assimilated or toxic elements are 

 the same as those eliminated without producing intoxication during 

 the incubation period following the first dose. This overassimilation 

 after anaphylaxis is the cause of the intoxication. 



Gay and Southard find much support for their contentions in the 

 results of experiments done with the so-called "passive" transfer of 

 hypersusceptibility. As mentioned above, hypersusceptibility may 

 be transferred to a normal animal with the blood serum not only of 

 a sensitive animal, but even more surely and effectually with that of 

 a refractory, or "antianaphylactic," animal. They believe that such 

 transfer is not "passive" but "active" sensitization, being accom- 

 plished by the transfer of "anaphylactin" to the normal animal. The 

 refractory animal has received more horse serum than the merely 

 sensitive one, since antianaphylaxis is produced by massive injec- 

 tions. Therefore its blood contains more anaphylactin and is con- 

 sequently more active in transferring sensitiveness. The fact that a 

 considerable incubation time is necessary in active sensitization they 

 attribute to the gradual action of the anaphylactin. 



In passive sensitization, therefore, they assumed a similar gradual 

 irritation of the vulnerable cells by the anaphylactin and, as we have 

 seen, obtained their reactions in animals so treated, usually 10 to 14 

 days after the sensitive serum had been given. This conception of 

 the mechanism of passive anaphylaxis was, of course, rendered un- 

 likely by the demonstrations by Friedemann, Otto, and others that 

 shock could be elicited in passively sensitized animals within 24 

 hours or less after transfer of the anaphylactic serum. 



To this, however, Gay and Southard 2 answer by implying that 

 this greater speed of development of sensitiveness in the experiments 

 of Otto is due to the larger doses used by him. They say "if the 

 doses are sufficient it (transmitted sensitiveness) may be shown in a 

 single day (Otto)." However, it is very likely that the sensitiveness, 

 noted by them in animals two weeks after the transference of ana- 

 phylactic serum was actually positive sensitization with antigen rests, 

 entirely comparable to the usual "Theobald Smith" phenomenon. 



x Gay and Southard. Jour. Med. Res., Vol. 16. 1907; Vol. 18, 1908; 

 Vol. 19, 1908. 



2 Gay and Southard. Jour. Med. Res., p. 427, 1908. 



