264 IXFLAMMATIUX, JiEGEXERATWX, GlWWTH 



formiiig- phagocj'tosis when properW stimulated, and apparently all or 

 nearly all lixed cells may act as phagocytes under some conditions. 

 Their power of independent movement is much less than their phago- 

 cytic power. Endothelial cells are particularly active in phagocyto- 

 sis, as also are the new mesodermal cells produced in inflammation. 

 Apparently they obey the same laws as the leucocytes, and not only 

 take up bacteria, but also fragments of cells and tissues, red corpus- 

 cles, and even intact leucocytes and other cells. Brodie •*- considers 

 that phagocj'tosis by endothelial cells in lymph-glands is the natural 

 end of the leucocytes, and red corpuscles seem to have a similar 

 fate. 



Phagocytosis is usually accomplished solely by the cytoplasm of the 

 cells, the nuclei maintaining a passive role; but, according to Detre 

 and Selli,^^ the phagocytosis of particles of lecithin is accomplished by 

 the nuclei, which seem to have a specific affinity for this substance. 



Giant-cell formation may also be considered as the result of chemo- 

 taxis, the cells moving toward the attracting particle, and when the 

 particle is larger than the cells they spread out upon its surface, their 

 cytoplasm flowing together because of altered surface tension. The 

 peripheral disposition of the nuclei probably depends on the fact 

 that in ameboid motion the nucleus of the cell plays an entirely passive 

 role, being dragged along by the cytoplasm, and hence it is located 

 most remotely from the attracting particle. Digestion of materials 

 taken into a giant-cell seems to go on as in the individual cells that 

 compose it.^* 



Influence of the Serum on Phagocytosis (Opsonins). — Phago- 

 cytosis of bacteria by leucocytes seems not to be merely a reaction be- 

 tween the leucocytes and the bacteria. Wright and Douglas have dem- 

 onstrated that certain substances in the blood-serum are necessary to 

 I)repare the bacteria for phagocytosis, these substances being termed 

 by them ''opsonins." If leucocytes are washed free from serum with 

 salt solution and let stand in a test-tube with such bacteria as Strep- 

 tococcus pyogenes, Staphylococcus pyogenes, B. typhosus, B. coli, B. 

 tuherculosis, and various other organisms, no phagocytosis occurs. If, 

 however, some serum from a normal or an immunized animal is added 

 to the mixture, active phagocytosis soon takes place. The action of 

 opsonins is also involved in phagocytosis by endothelium.^' The char- 

 acter and properties of the opsonins are further considered among the 

 reactions of immunity (Chapter vii). 



Results of Phagocytosis. — .After phagocytosis has been accom- 

 plished, the fate of the cir'nlfed object dei)ends ujion its nature. Tf 

 digestible by the intracelhdar enzymes it is soon destroyed, but in 



42 Jour, of Anat. and Phvsiol., 1901 (.•?;-)), 142. 

 4.^T{«rl. klin. \\ofh., ]nn.5"(42). 940. 



44 Spe Fabcr., Jour, of Path, and Pact., 1S9.3 (1). .149. 

 4'' Priscoe, Jour. Path, and Pact., 1907 (12), fit!. 



