276 INFECTION AND IMMUNITY. 



has a much larger molecule than lecithin itself. 

 His immunization of animals to produce an anti- 

 lecithid extended over a much larger period than 

 those of v. Dungern and Coea. 

 iiemoiysis Lecithin is a colloid, and in this connection it is 



by the Com- 

 bined AC- interesting to note that it may be used in combina- 

 tion of Col- ,. .., .. ., . -, . , ,1 



loids. tion with still another colloid in such manner that 

 the hemolysis which they cause is analogous to 

 that produced by hemolytic amboceptors and com- 

 plements. Landsteiner tried the effect of col- 

 loidal silicic acid on erythrocytes which were en- 

 tirely freed from serum, with the result that the 

 corpuscles were agglutinated under its influence. 

 It developed further, however, that colloidal silicic 

 acid not only acts as an agglutinin, but also simu- 

 lates a hemolytic amboceptor, and in the latter 

 capacity it may be activated either by the ordinary 

 complement of serum or by lecithin. Hence, we 

 have here an instance of the entire cytolytic action 

 being performed by two known chemicals, which 

 in their action appear to be analogous to ambocep- 

 tors and complements. Yet even the action of 

 these substances is obscure, for although the chem- 

 ical formula of silicic acid and lecithin are suffi- 

 ciently well known, the explanation of their activ- 

 ity as colloids is equally obscure with that of the 

 albuminous substances. 

 Nentraiiza- Another discovery which tends to brine: the 



tion Com- , J t , e 



piement by immune substances into closer touch with pure 

 ' chemistry is that of Hektoen concerning the abil- 

 ity of certain salts (calcium chlorid, barium 

 chlorid, etc.), to combine with complement in 

 such a way that the latter loses its activating and 

 combining function in relation to amboceptors. 

 This was mentioned incidentally under the sub- 



