FURTHER DEVELOPMENT OF KNOWLEDGE 195 



body, the "Bordetscher Antikorper," which is not identical with any 

 of the other known antibodies. 



In all experiments which deal with alexin fixation by specific 

 antigen-antibody complexes it is of the greatest importance that we 

 should guard against the errors easily introduced by fortuitous non- 

 specific antihemolytic agencies. Thus there are a number of factors 

 which will interfere with the functionation of alexin upon a sensi- 

 tized antigen, either by direct non-specific absorption of the alexin 

 itself or by producing physical conditions in the presence of which 

 alexin cannot act. 



Thus many animal tissue cells, in emulsion, will absorb alexin, 

 and the same property may be possessed by tissue extracts. Von 

 Dungern 97 was the first to call attention to this, and his observations 

 have been variously confirmed. Muir 98 showed that the stromata of 

 hemolyzed red blood cells exert strong anticomplementary action, 

 and that this is due to a firm union with the complement. It is not un- 

 likely that the action of cells in this respect is referable to their 

 lipoidal contents. This suggestion was first made by Landsteiner 

 and von Eisler," who found that the petroleum-ether extracts of red 

 blood cells possessed strong anticomplementary action which, to a 

 limited extent, was specific toward the particular corpuscles from 

 which the extracts had been made. Similar observations have been 

 made by Noguchi, 100 who speaks of the substance he extracts as "pro- 

 tectin." In general, the protective action of the lipoidal extracts 

 seems to depend largely upon cholesterin, and, since this substance is 

 present to some extent in many tissues, their antihemolytic action is 

 easily understood. In another section we have discussed the similar 

 neutralizing action of lipoidal substances upon poisons of various 

 kinds (saponin, tetanolysin, and snake poison), but, as we have noted 

 there, the neutralizing properties of the extracts do not, as a rule, 

 equal those of the whole tissues. 101 It is not unlikely that in such 

 cases as Landsteiner suggests the potent agent is not the lipoid itself 

 but rather a lipoid-protein combination, a class of substances of which 

 we know very little, but the importance of which, in many phases of 

 serum reactions, seems assured. 



We have already mentioned that yeast cells may absorb alexin. 

 And it has been found by Wilde 102 and others that almost all bac- 

 teria in emulsion may possess varying degrees of alexin-fixing prop- 

 erties even though unsensitized. There seems to be no regularity 

 either qualitatively or quantitatively in regard to this, but the fixa- 



97 Von Dungern. Munch, med. Woch., Nos. 20 and 28, 1900. 



98 Muir. "Studies in Immunity," London, Vol. 19. 



99 Landsteiner and von Eisler. Wien. kl Woch., No. 24, 1904. 



100 Noguchi. Journ. Exp. Med., Vol. 8, 1906, p. 726. 



101 See also Ivar Bang, "Bioehemie der Lipoide." 



102 Wilde. Berl. kl. Woch., 1901, Vol. 38, and Archiv f. Hyg., 39, 1902. 



