612 THE INTERNAL SECRETIONS AND IMMUNITY. 



are ingested alive Metchnikoff has shown. Spermatozoa, for 

 instance, ingested by macrophages were seen to continue their 

 motile activity until the tail had also been taken up. Begun 

 in 1865 with the digestive epithelium of Gedesmus bilineatus, 

 the cellular elements of which were shown to digest various 

 extrinsic substances, MetchnikofFs labors developed in 1883 

 into his present doctrine of phagocytosis, which, notwithstand- 

 ing much adverse criticism, is steadily gaining ground. 



The rapidity with which the protective process is carried 

 on in cases of general infection is well illustrated by Cantacu- 

 zene 3 : "Immediately after injecting anthrax bacteria in a vein 

 of a rabbit's ear," says this author, "the organisms are taken 

 up by phagocytes. At the end of seven minutes in the liver, 

 eight minutes in the lungs, and one hour in the spleen none 

 of the germs are free. Their destruction in the phagocytes 

 is at first very rapid, but soon some of the latter are overcome, 

 and the bacteria, by multiplying within them, cause them to 

 become centers of pullulation. Still, the bacteria that escape 

 from the dead phagocyte are seized by others; but, the number 

 of the former becoming greater as the battle progresses, their 

 protective powers are correspondingly reduced, and the bac- 

 teria finally invade the entire blood-stream. In the liver 

 . . . practically all the bacteria are destroyed and digested 

 within a few minutes after the injection. This superiority of 

 the hepatic phagocytes in the fray lasts almost throughout the 

 disease; but the activity of the phagocytes finally decreases; 

 the bacteria multiply within them and become generalized. 

 In the lungs there is rapid destruction of bacteria by poly- 

 nuclear cells, then intracellular development of bacteria and 

 generalization." 



The phagocytes just referred to, the microphages, are 

 wandering or migrating cells free to respond and travel more 

 or less promptly toward pathogenic bacteria, in virtue of the 

 chemotactic attraction possessed by the latter. 



Immediately connected with the role of these migrating 

 cells is the process of leucocytosis, a more or less transient or 

 marked increase, in a given area or organ, of leucocytes, the 



3 Cantacuzene: Quoted by Marcel Monnier, Gazette Medicale Beige, July 13, 

 1899. 



