562 IMMUNITY 



gives rise to sensibilisin as an anti-substance ; and when, after 

 a suitable time, fresh serum is injected, the anti-sensibilisin com- 

 bines with the sensibilisin, and thus the anaphylactic shock 

 results. In view, however, of the specific nature of the 

 phenomena, it would appear that both sensibilisinogen and anti- 

 sensibilisin must have the same special combining group for 

 sensibilisin, and it is accordingly difficult to see why the latter 

 should not also act as an antigen. He has also found that 

 when an animal is anaesthetised with ether the anaphylactic 

 shock may be averted. Other workers at this subject 

 hold that there are only two substances concerned, and 

 some consider that the phenomena depends on a process of 

 precipitation. Friedberger, for example, considers that the real 

 toxic agent is formed by the action of complement on serum- 

 precipitate (antigen + precipitin). To this substance he gives the 

 name " anaphylatoxin," and in support of his view he has shown 

 that guinea-pig's complement, after it has been allowed to 

 act for some time on such a precipitate and then removed by 

 the centrifuge, has acquired toxic properties, and produces the 

 symptoms of anaphylaxis when injected into a normal guinea 

 pig. He also points out that during anaphylactic phenomena, 

 especially in the case of passive anaphylaxis, there is a great 

 fall of complement in the blood of the animal, and Scott has 

 brought forward facts which indicate that there is a close 

 relationship between this fall in complement and the occurrence 

 of the symptoms in anaphylaxis. On the other hand, Gay and 

 Southard do not believe in the theory of a reaction-body. 

 They consider that the condition depends on the presence of a 

 substance in the serum which they call anaphylactin, and which 

 persists in the blood of the guinea-pig for a long period of time. 

 This acts as a slight irritant to the nerve-cells, and produces in 

 them an increased affinity for certain molecules in the serum. 

 Accordingly, when the second injection is made, the rapid com- 

 bination of these molecules with the cells results in the disturb- 

 ances described. This view has, however, received little support, 

 and there are various facts against it, especially in relation to 

 the transference of anaphylaxis. Others, again, e.g. Citron, 

 consider that supersensitiveness is so closely allied to immunity 

 as to really represent the earliest stage in its development. At 

 present it is impossible to express an opinion with regard to the 

 real nature of the phenomena. Manifestly, however, if they 

 depend upon the existence of an anti-substance in the nerve : cells 

 and the cells of other organs, the injection of fresh serum, before 

 the anti-substance is fully formed, say on the ninth day after 



