310 INFECTION AND IMMUNITY. 



hemolytic serum. Following such an injection into 

 the peritoneal cavity there occurs a great accession 

 of macrophages which ingest the erythrocytes, dis- 

 solve the hemoglobin and eventually digest the 

 stroma. The same phagocytes are involved in the 

 resorption of any other foreign cells of animal ori- 

 gin which may be injected. In view of the intracel- 

 lular hemolysis by the leucocytes, one may suspect 

 that the latter contain a hemolytic ferment; one 

 which, perhaps, is analogous to the hemolysin 

 (hemolytic amboceptors and complement) of 

 Formation serums. On this point there has been sharp dis- 

 cussion. Metchnikoff cites observations to show 

 that a ferment of this nature may be extracted 

 from the lymphoid organs, that it contains a heat- 

 susceptible constituent, and that when fresh it 

 may be used to reactivate a heated hemolytic 

 serum. This would indicate that the leucocytes 

 contain cytase (complement), but it is not clear 

 that they would also contain the fixators (ambo- 

 ceptors). Nevertheless, the demonstration of an 

 intraleucocytic hemolysin and a knowledge of the 

 phagocytic power of the leucocytes for erythro- 

 cytes form the basis for MetchnikofFs belief that 

 serum-hemolysin is nothing more than intraleuco- 

 cytic hemolysin, which under proper conditions 

 may reach the serum or plasma. By an extension 

 of this conception it is held that all cytolysins are 

 produced by the macrophages. 



Thermosta- Korschun and Morgenroth, on the other hand, 

 f 2S?* orI obtained from lymphoid and various other organs, 

 Extracts. not ft thermo i a bii e hemolysin, but one which with- 

 stands prolonged boiling a coctostabile hemolysin 

 which is soluble in alcohol, shows no amboceptor- 



