CYTOLYSINS 141 



glutinative than hemolytic. The phytotoxins resemble some of the 

 bacterial hemotoxins in that they may serve as antigens for the pro- 

 duction of antitoxins but differ in that, as a rule, they are thermostable. 

 Both groups act according to the law of multiple proportions. Of 

 considerable importance from the experimental point of view are the 

 saponins " a closely related group of glucosides found in at least 

 forty-six different families of plants" (Wells). They are thermo- 

 stable, do not act as antigens, have a fairly definite chemical composi- 

 tion and are in these particulars to be separated from true toxins. They 

 operate injuriously not only upon the erythrocytes but also on other 

 body cells, especially those of the central nervous system. Cholesterol 

 and lecithin both combine with saponin, the former in such a way as 

 to prevent hemolysis. Therefore, it is assumed that the hemolytic 

 action of saponin is dependent upon its action on the stroma lipoids. 

 Normal serum is anti-hemolytic for some of the saponins, a property 

 which may be slightly increased by careful immunization; Robert be- 

 lieves this increase to be due to an increase of blood cholesterol. 



Venom Hemolysins. The venom hemolysins or hemotoxins are 

 found in different amounts in all venoms, and the phenomenon of venom 

 lysis is of considerable importance not only because of its scientific 

 interest but also because of its employment in certain clinical tests. 

 The venoms possess not only lytic but also hemagglutinative properties, 

 the two usually being present in inverse ratio. Flexner and Noguchi 

 demonstrated that the lysin of venoms requires activation by some 

 substance which exercises a complementary power. They found that 

 cobra hemotoxin dissolves the red corpuscles of certain animals (ox, 

 sheep and goat) only in the presence of serum,, but that it may dis- 

 solve other erythrocytes (dog, guinea-pig, man, rabbit, horse) in the 

 absence of serum. This difference is probably due to a content of 

 activator in the latter cells, which activator must be furnished by serum 

 for the lysis of the former cells. Kyes found that he could extract 

 an activator from those cells which do not require serum for venom 

 lysis but was unable to do so in the case of those cells which require 

 serum activation. This activating substance was found to be ether 

 soluble. Kyes subsequently found that lecithin can activate venoms and 

 assumed that this lipoid constituted the bulk of the activating sub- 

 stance. The substance in serum is usually active only after the serum 

 has been heated, but with some sera heating is not necessary. Kyes 

 and Sachs believed this to be due to differences in the nature of the 

 lecithin union in the serum. Kyes mixed cobra poison with a chloro- 

 form solution of lecithin and obtained a substance which he named 

 cobra lecithid capable of activating cobra venom. Von Dungern and 

 Coca, upon investigating the subject, came to the conclusion that the 

 cobra venom contains a ferment capable of splitting the lecithin so 

 as to yield certain substances such as oleic acid and that the resulting 

 hemolysis is due to the activity of these secondary substances. Noguchi 

 holds that although lecithin exists in the stroma of red blood-cells it 

 is not present in a form available for venom activation and that the 



