356 STUDIES IN IMMUNITY. 



definite experimental demonstration that deviation of the alexin 

 may exist in hemolysis under conditions absolutely identical to 

 those described for bacteriolysis by Neisser and Wechsberg, will 

 appear presently in the Pasteur Annals.* I may note simply that 

 it is indeed the conjectured role of precipitates that does cause this 

 alexin deviation in hemolysis. 



CONCLUSIONS. 



1. As was noted by Gengou, the serum of an animal of species 

 A, injected with the blood serum of species B, contains specific 

 "substances sensibilisatrices " which, when the immune serum A 

 is mixed with serum B, forms a complex which fixes alexin. This 

 alexin-fixing substance is the specific serum precipitate formed by 

 the interaction of the two sera. 



2. Repeated washings of blood with relatively large amounts of 

 physiological solution are necessary to remove all traces of serum. 

 A very small amount of this serum contains enough precipitinogen 

 to form a large precipitate if enough precipitin (immune serum) 

 be present. 



3. The formation of a serum precipitate does not affect the sen- 

 sitizing strength of the hemolytic immune body. 



4. The so-called " anticomplements of normal sera" of Sachs 

 and probably also the "antagonistic substances" of Pfeiffer and 

 Friedberger are simply specific serum precipitates capable of fixing 

 alexin. 



5. A disregard of the presence and the alexin-fixing properties 

 of serum precipitates has doubtless given rise to many erroneous 

 impressions of the mechanism of hemolysis. 



* See p. 357. 



