194 HEMO LYSIS AND SERUM CYTOTOXINS 



Hemagglutinin. Agglutination of red corpuscles occurs 

 under the influence of immune serum as well as under the influ- 

 ence of some normal serums. In all respects the principles 

 seem to be the same as those described for bacterial aggluti- 

 nation. Agglutination occurs at much lower temperatures than 

 hemolysis, and also is not checked by heating the serum to 55; 

 hence it is possible to observe hemagglutination independent of 

 hemolysis. Serums may contain hemagglutinins and not be 

 hemolytic ; the reverse is also true. As agglutination occurs in 

 corpuscles that have been fixed in formalin or sublimate, it is 

 probably not the proteids that are affected, but some other of 

 the ingredients of the stroma, of which lecithin and cholesterin 

 seem to be the chief. 



Certain vegetable poisons also produce agglutination of red 

 corpuscles, especially ricin, abrin, and crotin, and the fact that 

 ricin has little or no hemolytic action shows the independence 

 of the processes. Snake venoms contain agglutinins, destroyed 

 by heating to 75; their agglutinating power being in inverse 

 ratio to their hemolytic power. Corpuscles agglutinated by 

 venoms may be again separated by potassium permanganate 

 solutions. 1 Silicic acid and certain other colloids may act as 

 agglutinins, their effects bearing a relation to the effects of 

 electrical charges upon agglutination of bacteria or of colloids 

 (q. V.).* 



Agglutination of the corpuscles during life may be of some 

 pathological importance, for such masses of agglutinated cor- 

 puscles may readily produce capillary thrombi and emboli, 

 which, if wide-spread, may create much disturbance. Many bac- 

 teria produce substances that are agglutinative for human red 

 corpuscles, among them being B. typhosus, pyocyaneus, and 

 staphylococcus. Flexner 3 has found in typhoid fever thrombi 

 that seemed to be composed of agglutinated red corpuscles, 

 almost free from fibrin and leucocytes. Probably many of the 

 so-called " hyaline thrombi " found frequently in infectious 

 diseases are really composed of agglutinated, partly hemolyzed 

 red corpuscles (see " Thrombosis," Chap. xi). 



HEMOLYSIS BY BACTERIA 



Both pathogenic and non-pathogenic bacteria produce hemo- 

 lytic substances that are excreted into the fluids in which they 

 grow. During many infectious diseases marked hemolysis occurs, 



1 See Flexner, Univ. of Penn. Med. Bull., 1902 (15), 361 and 324. 



2 See Landsteiner and Jagic, Munch, med. Woch., 1904 (51), 1185. 



3 Univ. of Penn. Med. Bull., 1902 (15), 324; Amer. Jour. Med. Sci., 1903 

 (126), 202. 



