468 COLLECTED STUDIES IN IMMUNITY. 



By following up a very important observation made by Cal- 

 mette, 1 that the complementing action of a serum, in contrast to 

 what is seen with ordinary complements, is still preserved after heating 

 to 62 C., we succeeded in discovering what this complementing agent 

 was, and proved that lecithin was able to activate the cobra venom 

 amboceptor. Especially were we able to show that the divergent 

 behavior ot the various species of blood- cells (some of them, ox blood, 

 goat blood, sheep blood, are not dissolved by cobra venom alone, 

 while others, such as guinea-pig blood, rabbit blood, human blood, 

 dog blood, are dissolved under these circumstances) is due exclusively 

 to the lecithin, only those blood- cells being dissolved in which the 

 lecithin is so loosely bound that it is available for the activation of 

 the cobra -venom amboceptor. 2 



An exact study of these activating phenomena by means of lecithin 

 seemed to us to be of the highest importance for one of the fundamental 

 problems of immunity, namely, the mode of action of complements. 

 Every one who has had any large experience with the activation of 

 ordinary haemolytic amboceptors by means of complements, and 

 who compares this activation with that of cobra venom by means of 

 lecithin, will be surprised at the complete similarity of both processes, 

 and will not doubt that essentially the same mechanism must control 

 both. For some years the schools of Bordet and Ehrlich have had 

 a sharp conflict of opinion concerning the explanation of the funda- 

 mental facts observed by Ehrlich and Morgenroth, that the amboceptor 

 is anchored by the red blood- cells, thus making the blood-cells sus- 

 ceptible to the action of the complements. For numerous- reasons 

 which are given in the earlier studies, Ehrlich's school assumes that 



1 Calmette, Compt. rend, de 1'Acad. des Sciences, T. 134, No. 24, 1902. 



9 Some time ago we confirmed the observations of Flexner and Noguchi, 

 that blood-cells unsusceptible to cobra venom alone can be activated by certain 

 fresh sera, and that this activatibility is then lost on heating the sera to 56 C. 

 In conformity with these authors we assumed that the cobra venom could 

 also be activated by true complements. At present, however, we have become 

 rather skeptical as to the correctness of this explanation. We cannot at once 

 dismiss the assumption that the action is an indirect one, the action of the 

 serum causing the lecithin combination in the red blood-cells to become looser, 

 so that then this substance can exert its activating power on the amboceptor. 

 This finds further support in several observations which we have made on 

 the favoring influence of certain indifferent substances (oils, pure fatty acids) 

 on haemolysis with cobra amboceptor. In these cases the cause of the solu- 

 tion can only be a change in the character of the lecithin combination. 



