358 STUDIES IN IMMUNITY. 



evident in bacteriolysis has never been shown to exist in hemolysis. 

 The experiments by Morgenroth* demonstrating such a phenomenon 

 in hemolysis are evidently incorrectly conceived, as Bordetf has 

 shown, and should not.be admitted as evidence. 



The interpretation we wish to offer of this Neisser and Wechsberg 

 phenomenon has an evident relation to certain experimental results 

 that have already been described.! These experiments dealt with 

 the alexin-fixing action of the albuminous precipitates obtained by 

 mixing a precipitin serum with the proper antigen. The results 

 may be summarized as follows : 



1. Gengou showed that the serum of animals of species A 

 immunized against an albuminous substance of species B has not 

 only a precipitating property for these substances, but also endows 

 them with the property of absorbing alexin. These albuminous sub- 

 stances treated with the specific immune serum act, in other words, 

 as do blood corpuscles or bacteria treated with suitable sensitizers. 



2. We were able to carry Gengou's observations farther by show- 

 ing that the fixation of alexin in this instance is brought about 

 exclusively by the precipitated albuminous substances and not by 

 those in solution. 



3. It is worth noting that a very weak dilution of precipitinogen 

 (precipitable serum) in salt solution will give a relatively abundant 

 precipitate with a suitable dose of precipitin. To avoid the occur- 

 rence of a serum precipitate in hemolytic experiments, it is indis- 

 pensable to wash the corpuscles employed several times with salt 

 solution to remove the accompanying serum entirely. This serum 

 if present will form a precipitate with the immune serum used to 

 sensitize the blood corpuscles in such an experiment. 



4. This precaution in washing has apparently not been taken 

 by many investigators ; as a result, in their mixtures of incompletely 

 washed blood (that is, blood containing traces of serum) and hemo- 

 lytic substances (sensitizer and alexin) a precipitate was formed 

 that could independently fix a greater or less amount of the alexin 

 employed. This fixed alexin would, of course, not affect the cor- 

 puscles, and consequently a true deviation of alexin would have 

 occurred in a hemolytic experiment. 



* Centralblatt f. Bakt., XXV, 1904, 501. f See p. 299. 



% See p. 346. $ See p. 241. 



