PHAGOCYTOSIS 



277 



the neuroglia tissue, and, in fact, all phagocytic cells which are 

 ordinarily confined to some definite localization in the body. Among 

 phagocytic cells Metchnikoff further distinguishes between "micro- 

 phages," by which he designates the polymorphonuclear leukocytes 

 of the circulating blood and 

 "macrophages." The ma- 

 crophages include the fixed 

 cells mentioned above, to- 

 gether with the large mono- 

 nuclear elements of the 

 blood, in short, all phago- 

 cytic cells except the micro- 

 phages. 



Although no absolute 

 functional differentiation is 

 possible between the two, it 

 is true, in a general way, 

 that the microphages are 

 concerned primarily with 

 the phagocytosis of bacteria 

 and especially of those POLYNUCLEAR LEUKOCYTES TAKING UP STA- 

 which invade acutely, while PHYLOCOCCI. 



the macrophages are con- 

 cerned especially with the resorption of cellular detritus, foreign 

 bodies, and such bacteria as are more chronic in their activities, or 



are peculiarly insoluble. 

 On the other hand, micro- 

 phages may take up foreign 

 particles and bacteria of all 

 kinds under suitable condi- 

 tions, and no sharp line can 

 be drawn between the two 

 varieties in this respect. 

 Metchnikoff further be- 

 lieves that the two classes 

 of phagocytic cells differ in 

 the nature of the protective 

 substances they secrete and 

 furnish in the blood 

 plasma. This, however, is 

 a problem concerning which 

 there is much difference of 

 opinion and which calls for 

 separate discussion in an- 

 other place. 



The property of phago- 



KUPFER CELLS CONTAINING MALARIAL PIG- 

 MENT. DIAGRAMMATIC ALLY DRAWN PROM 

 A SECTION OF MALARIAL LIVER KINDLY 

 FURNISHED BY DR. E. LAMBERT. 



