138 



MICROBES AND TOXINS 



Fig- 



Metchnikoff has divided the phagocytes into macrophages 

 and microphages ; the former are chiefly concerned in the 

 absorption of cells and cellular debris, and include the large 

 mononuclears, the fixed phagocytes of the spleen, of the 

 peritoneum and of the lymphatic glands. They digest the 

 blood corpuscles and other phagocytes. The microphages 



are the polymorphs ; their 

 principal function is to 

 digest bacteria. There are 

 exceptions. In certain 

 cases the microphages take 

 up cells (red cells among 

 others), while in certain 

 cases the macrophages 

 take up bacteria ; the large 

 mononuclears surround the 

 tubercle bacillus producing 

 the giant cell, and take up 

 also the spirochaetes of 

 recurrent fever and of 

 syphilis. 



It has sometimes been 

 maintained that the pha- 

 gocytes only take up dead 

 bacteria and not living virulent ones ; this is a mistake to 

 which it will be necessary to refer again in connection with 

 immunity. Under the microscope there can be seen inside 

 the phagocytes living and even motile bacilli, and cultures 

 can be obtained by inoculating into broth phagocytes full of 

 microbes : the leucocytes are destroyed and the liberated 

 bacteria multiply. They were still quite alive therefore, 

 although already seized by the phagocytes. 



The phagocytes secrete digestive ferments. Rossbach has 

 demonstrated the existence of a starch-splitting ferment in the 

 leucocytes of the tonsils. The cells of pus can digest fibrin 

 and gelatine, and must thus secrete proteolytic ferments. In 

 cases of acute muscular atrophy the progressive digestion of 



5 



, 52. — Different leucocytes. — i. 

 Polymorph. — 2. Microphage (poly- 

 morph) taking up staphylococci, s(. 

 — 3. Small lymphocyte. — 4. Eo- 

 sinophil. — 5. Large mononuclear 

 (macrophage). — 6. Macrophage 

 from the peritoneum of a guinea- 

 pig taking up red corpuscles. — 7. 

 Macrophage from the peritoneum 

 taking up polymorphs (micro- 

 phases) and blood corpuscles. 



