174 INFECTION AND RESISTANCE 



with these experiments, however, Liefmann experimented on frogs; 

 in whom, as Friedberger has shown, extirpation of the liver is not 

 so rapidly fatal as in warm-blooded animals. He removed the livers 

 of frogs in a number of cases and, although his animals lived about 

 a week, there was no definite diminution of the hemolytic properties 

 of the serum. It seems, therefore, that the origin of alexin in the 

 body is by no means settled and requires further investigation. 



Equally unsatisfactory have been the attempts to define the chem- 

 ical nature of the complement or alexin. In the investigations deal- 

 ing with the hemolytic action of cobra venom it seemed at first as 

 though a clue to this problem had been found. Flexner and Nogu- 

 chi 28 made the interesting observation that cobra poison alone does 

 not hemolyze the blood cells of certain animals, namely those of 

 cattle, goats, or sheep, if these cells are washed entirely free of 

 serum. This seemed to suggest that the serum of these animals con- 

 tained some activating substance. It also seemed to indicate that the 

 cells of other animals, which were easily hemolyzed, even when en- 

 tirely freed of serum, might contain such an activating substance 

 within themselves. The behavior of this activating substance toward 

 snake-venom hemolysis was therefore very similar to the action of 

 complement, except in one important respect, namely, as Calmette 29 

 showed, almost all sera were rendered more efficient for the activa- 

 tion of snake venom when heated to 65 C., whereas complementary 

 properties of sera for other hemolyzing complexes are, of course, 

 destroyed at 56 C. Kyes, 30 31 on further studying these phenomena, 

 extracted the red blood cells of rabbits and other animals whose cells 

 were hemolyzed by snake venom alone, by shaking them up with 

 distilled water, and showed that, with these extracts, he could activate 

 the venom against ox, goat, and sheep corpuscles, cells which were 

 not ordinarily hemolyzed by the venom without the addition of 

 serum. Similar activation of the venom with extracts of the ox, 

 goat, or sheep corpuscles was not possible. He concluded from this 

 that the blood cells of the rabbit, dog, guinea pig, and man pos- 

 sessed an "endocomplement" for the snake venom; that is, a com- 

 plementary substance contained within the cells, while in the other 

 species it was found in the activating serum only. 



The thermostability of such venom "complements" encouraged 

 him to attempt their isolation, and he found that they were ether- 

 soluble, indicating their lipoidal nature; and, finally, after several 

 negative attempts with activation by other lipoids, he determined 

 that lecithin, added to the corpuscles and the snake venom, brought 



28 Flexner and Noguchi. Journ. Exp. Med., Vol. 6, 1902 ; Univ. Pa. Med. 

 Bull, 1902 and 1903. 



29 Calmette. C. R. de VAcad. des Sciences, p. 134, 1902. 



30 Kyes. Berl klin. Woch., Nos. 38 and 39, 1902. 



31 Kyes and Sachs. Berl. klin. Woch., Nos. 2-4, 1903. 



