352 CYTOLYSINS 



suggests a ferment-like activity. They differ from true prqteolytic fer- 

 ments, such as trypsin, in not digesting the stroma of corpuscles, al- 

 though recent work by Dick would seem to indicate that proteolysis 

 actually occurs, a process that increases the permeability of the cell and 

 permits the escape of hemoglobin. 



On the other hand, it is possible that the nature and action of com- 

 plements may be placed upon a chemical basis. Following the dis- 

 covery of the hemolytic power of cobra venom by Flexner and Noguchi, 

 a power they ascribed to the presence of an amboceptor in the venom 

 acting with serum complement, Kyes found that the amboceptor may 

 be activated not only by a complement in the blood-serum, but also by 

 some constituent of the red blood-corpuscles themselves. This last 

 observer speaks of the latter as endocomplement, i. e., endocellular com- 

 plement. 



In attempting to discover the nature of this endocomplement various 

 substances existing normally in the erythrocytes, such as cholesterin and 

 lecithin, were obtained in a pure state and their activating powers for 

 cobra amboceptors tested. These investigations showed that lecithin 

 has an activating power, whereas cholesterin is antihemolytic. Al- 

 though all erythrocytes contain lecithin, yet all are not equally suscep- 

 tible to the action of venom amboceptors, which is probably due to the 

 fact that the lecithin in the cells of some animals is bound to other cell 

 constituents in a loose way and is thus available as complement. In 

 syphilitic infection the lecithin content of the erythrocytes is actually 

 diminished or in some manner rendered less available, so that the in- 

 hibition or absence of venom hemolysis is diagnostic of this infection. 



Kyes was able to obtain the union of cobra amboceptor and lecithin, 

 forming what is known as cobra ledihid. Although lecithin is an unstable 

 substance and is difficult to obtain free from fatty acids and soap, there 

 is little doubt but that Kyes' lecithid is a phosphatid compound and is 

 actively hemolytic after all traces of fatty acids have been removed. 



The next important observations were made by Noguchi, 1 who found 

 that soap isolated from blood and various tissues possessed active he- 

 molytic properties. The salts of the fatty acids, and particularly of oleic 

 acid, were found to possess similar hemolytic properties. Pure soluble 

 oleates mixed with serum were found to produce compounds possessing 

 many of the characteristics of true complements: (1) They are inacti- 

 vated by heating to 56 C. for half an hour; (2) they are inactive at 

 C.; (3) the addition of acids, alkalis, and yeast renders them inactive. 

 1 Proc. Soc. Exper. Biol. and Med., 1907, 4, 107; Biochem. Zeitschr., 1907, 6. 



