190 INFECTION AND RESISTANCE 



and Martin, 82 and it may well be doubted, as a result of these and 

 other researches, whether we are at all justified in assuming the ex- 

 istence of anticomplements. 



The work of Gay, published independently in the same year as 

 that of Moreschi, has, in a general way, the same significance, but 

 Gay recognized the relation of the conditions observed by him to the 

 precipitin reaction, a feature absent from both the original study of 

 Gengou and the work of Moreschi. Gay noticed that an inactivated 

 hemolytic immune serum, left for some time in contact with its spe- 

 cific cells, and then separated from them by centrifugation, would 

 often possess anticomplementary or anti-alexic properties. He fur- 

 ther noted that after such a serum had been freed from the cells by a 

 short centrifugation, if it was again vigorously centrifugalized, a 

 slight, cloudy sediment would appear at the bottom of the tubes. If 

 this sediment was removed the serum lost its alexin-fixing properties. 

 He recognized that the precipitate formed in these tubes was a spe- 

 cific precipitate resulting from the union of a precipitinogen and its 

 antibody. The reaction was due entirely to the fact that insufficient 

 washing of the cells used in producing the hemolysin, gave rise to 

 the formation of precipitin against the serum of the animal from 

 which the cells had been taken, and subsequently insufficient washing 

 of the cells of this same species employed in the tests furnished 

 enough antigen to give a precipitin reaction in the tubes in which 

 the inactivated hemolytic (and precipitating) serum was mixed with 

 the cells. Subsequently, numerous investigations 83 have shown 

 Gay's interpretation to be correct, and we may now accept it as a 

 fact that precipitates formed by the union of specific antigen with 

 its antibody possess the power of fixing alexin and that, in a general 

 way, this fixation is proportionate in energy to the amount of pre- 

 cipitate which is formed. 



Gay utilized his results primarily to contradict certain assertions 

 of Pfeiffer and Friedberger concerning antibacteriolytic substances 

 supposed to occur in normal sera. These authors had found that, if 

 normal sera possessing no "antagonistic" properties in the first place 

 were left in contact with certain bacteria, they acquired antibac- 

 teriolytic properties for these particular bacteria. Thus normal 

 inactive rabbit serum, left in contact with typhoid bacilli, and again 

 separated from the bacteria, now prevented the lysis of sensitized 

 typhoid bacilli if tested by the intraperitoneal method spoken of as 

 the Pfeiffer reaction. Sachs 84 applied these observations to analo- 

 gous hemolytic reactions and obtained similar results. He found 

 that, if normal, inactive rabbit serum was left in contact with sheep 



82 Muir and Martin. Journ. of Hyg., Vol. 6, 1906. See also Muir's 

 "Studies on Immunity," Froude, London, 1909. 



83 Dean. Zeitschr. f. Imm., I, Vol. 13, 1912. 



84 Sachs. Deut. med. Woch., 1905, No. 18. 



