THE ADRENALS AND BUCHNER'S ALEXINS. 627 



Pfeiffer's conclusion that the bactericidal power resides in 

 the serum, therefore, was not unwarranted, although the local 

 leucocytosis that available from the immediate surroundings 

 through the chemotactic influence of the pathogenic germs in- 

 troduced might have sufficed to account for the destruction of 

 the latter. Yet, how was the field so rapidly cleared of leuco- 

 cytes as it was, and what was the origin of the granular detritus ? 

 Granting that the fluid did possess microbicidal properties, how 

 could Pfeiffer explain the presence of bacteria within phago- 

 cytes, which presence he had himself witnessed? The fact that 

 these organisms were, dead led him to conclude that phagocytes 

 were really only scavengers, and that they ingested dead bac- 

 teria after the serum had killed them. Hence, to the serum 

 belonged, in his opinion, all the bactericidal power. 



Metchnikoff, 17 while recognizing the strength of Pfeiffer's 

 observations in respect to the ability of the peritoneal effusion 

 to kill germs, showed that leucocytes capable of acting as 

 phagocytes in the peritoneal cavity were accumulated in masses 

 on the surrounding free surfaces, and that those damaged dur- 

 ing the fray could easily be detected in the serous fluid if the 

 latter were withdrawn in from two to six minutes after the 

 injection. The colored plate opposite page 628 is interesting in 

 this connection. Metchnikoff further showed that these dam- 

 aged leucocytes were nevertheless able to destroy them by their 

 secretions: a feature which explained the bactericidal property 

 of the liquid. All these facts have since been demonstrated 

 by a large number of experiments. The doctrine of phago- 

 cytosis has remained unassailed, . . . but so has Pfeiffer's 

 view. 



Denys showed that the bactericidal property of the serum 

 increased or decreased according to the number of leucocytes 

 present. Anthrax bacilli placed in small bags permeable only 

 to the fluids of the blood and introduced into various bodily 

 fluids were found to be dead when withdrawn. Metchnikoff 

 and Bordet were led to conclude that this was due to the pres- 

 ence, in the blood-serum, of a substance, "microcytase," which 

 was always found in plasma rich in phagocytes, and was in- 

 variably absent, however, when these cells were also absent. 



17 Metchnikoff: Annales de 1'Institut Pasteur, June 25, 1895. 



