522 THE RELATION OF COLLOIDS AND LIPOIDS TO IMMUNITY 



found that an ethereal extract of red corpuscles contains a substance 

 that inhibits saponin hemolysis. This substance consists largely of 

 cholesterin, and it is the presence of cholesterin in normal serum that 

 inhibits saponin hemolysis. This may be demonstrated experimentally 

 by adding cholesterin to a solution of a saponin. Noguchi 1 has shown 

 that lecithin does not possess the same antihemolytic action on saponin. 

 It would appear, therefore, that saponin causes hemolysis by combining 

 with, altering, or dissolving the lipoids of the stroma of corpuscles. The 

 resistance of corpuscles to saponin hemolysis varies in certain diseases, 

 being especially low in jaundice (McNeil) 2 . 



While saponins, solanins, phallin, and other vegetable poisons are of 

 relatively simple chemical composition and quite unlike proteins, 

 enzymes, or toxins, it is possible that bacterial and vegetable hemo- 

 toxins, such as tetanolysin, abrin, ricin, crotin, and robin, may produce 

 their effects by a similar action on the lipoids of the erythrocytes. 

 Noguchi has shown that cholesterin inhibits the action of tetanolysin. 

 Landsteiner and Bottori have found that protagon, a brain lipoid, 

 possesses the property of binding tetanus toxin, which indicates that 

 this toxin may produce its effects by some action upon the lipoids of 

 nerve-cells. 



(c) The important relation of lipoids to the Wassermann reaction and 

 certain precipitin or floccule-forming reactions (Klausner, Porges-Meier, 

 Hermann-Perutz) has been mentioned repeatedly. Just what role the 

 lipoids play in these phenomena is not known. While the globulins of 

 syphilitic serums are strongly suspected of being concerned in these 

 processes, their relation is not clear. Klausner 3 now believes that the 

 precipitate that forms when distilled water is added to syphilitic serum 

 is due to the higrrlipoid content. 



THE EPEPHANIN REACTION 



Principle. This reaction is based upon the observation made by 

 Weichardt 4 in 1908; he found that diffusion is accelerated when dif- 

 ferently colored solutions of antigen and its specific antibody are brought 

 together. Changes in diffusion are associated with changes in the 

 surface tension, both of which depend on a change in the osmotic pres- 

 sure. This is the principle made use of by Ascoli in his miostagmin 

 reaction, which will be described further on. 



1 Univ. of Penna. Med. Bull., 1902, 15, 327. 



2 Jour. Path, and Bact., 1910, 15, 56. 3 Biochem. Zeit.,'1912, 47, 36. 

 4 Berl. klin. Wochenschr., 1908, No. 20; Centralbl. f. Bakteriol., xliii, 143; ibid., 



xlvii, 39; Zeitschr. f. Immunitatsforsch., 1910, vi, 651; Deutsch. med. Wochenschr., 

 1911, No. 4, 154. 



