A GENERAL REVIEW OF THE RECENT WORK IN IMMUNITY. 581 



has the affinity of its cytophile group increased, so that now it is able 

 to unite with the cells. Thus far, such observations have been made 

 only on normal amboceptors; and this fact explains why the numerous 

 attempts of various authors to separate normal haemoly sins, by means 

 of absorption at low temperatures, have failed. 1 The amboceptors 

 obtained by immunization, on the other hand, regularly possess a 

 high affinity for the cell-receptor. This is easily understood if we 

 consider their mode of origin, for we may perhaps see in this a selec- 

 tion of the groups with the highest affinity. Certainly in this case 

 the exception proves the rule; for the mere fact, that in some instances 

 the amboceptor does not unite with the cell until it has first com- 

 bined with the complement, at once shows that we cannot be dealing 

 with a sensitization. On the contrary, this shows that the ambo- 

 ceptor is an interbody in the strict sense of the word. These condi- 

 tions have been most clearly brought out by the experiments of 

 Preston Kyes on cobra venom. The researches of Flexner and 

 Noguchi, as we all know, showed that cobra venom by itself is no 

 hsemolysin, but plays the role of amboceptor in haBmolysis. The 

 most important of the activators is the one discovered by Kyes, 

 namely, lecithin. The relation between snake venom and lecithin is 

 really the same as that between amboceptor and complement; but 

 the former possess one great advantage for chemical analysis, they 

 are both stable substances, and thus contrast strongly with the highly 

 susceptible substances found in blood serum. Hence what was 

 impossible in the case of the latter could readily be effected with 

 cobra venom. Kyes, it will be remembered, has demonstrated, ad 

 ocular, the direct union of cobra amboceptor and lecithin comple- 

 ment, and has furthermore succeeded in isolating the resulting com- 

 bination, the cobra-lecithid, in pure form. 2 



Thus, for the first time, the conclusion was reached chemically 



1 In this connection I should also like to mention the interesting atypical 

 behavior discovered by Donath and Landsteiner in the amboceptor reaction. 

 These authors observed hsemolytic autoamboceptors in the serum of a patient 

 suffering from paroxysmal ha?moglubinaria. These autoamboceptors, how- 

 ever, only united with the bloods at low temperature. 



2 Kyes has recently continued his studies at my laboratory, and has demon- 

 strated the important fact that in this formation of cobra-lecithid there is a 

 true chemical synthesis. The course of this synthesis is such that a fatty acid 

 radical is split off from the lecithin molecule, whereupon the residual combina- 

 tion, which corresponds to a monostearyllecithin, unites with the cobra ambo- 



