116 



INFLAMMATION. 



FIG. 43. PHAGOCYTES. 

 These are leucocytes which 

 have taken particles of pigment 

 into their bodies. 



Before considering the way in which repair of a wound is effected, we 

 shall look at an important class of cells in the body by which foreign and 

 waste substances are disposed of. 



PHAGOCYTES. The disposal of small foreign 

 particles which in one way or another get into 

 the body, and the removal of dead and useless 

 fragments of tissue which may be present as the 

 result of injury or disease, are cared for by 

 larger and smaller cells, called phagociftes. To 

 a certain extent the same occurs in the wear and 

 tear of normal life. The cells having this mat- 

 ter in charge are largely leucocytes (Fig. 43), 

 and all are apparently mesodermal, lowly or- 

 ganized cells. Some of them are large cells and may be multiuuclear 

 the so-called "giant cells" ' (Fig. 44). Eudothelial cells may also play 

 an important role as phagocytes. 



The disposal of dead or foreign material is in part accomplished by its 

 being taken into the bodies 

 of the phagocytes. These 

 may either retain it more 

 or less permanently, or may 

 absorb it in virtue of their 

 metabolic powers, or, in the 

 case of leucocytes, may carry 

 it off to some region of de- 

 posit by the exercise of their 



amosboid capacities. On the & ^> ' "'' * 0> 

 other hand, the leucocytes, \& .&' <jj& .& ^ 



and possibly other mesoder- /v y '^ v * fc >J : sp 



mal cells, may either with - ' r ; '.^-^.> 



or without disintegration ^T 5 ^^^ 



develop ferment-like sub- 

 stances 2 which render pro- 

 teid materials soluble ; thus 

 dead or useless tissue frag- 

 ments may be dissolved and 

 carried off in the tissue fluids (Fig. 45). This phagocytic and lytic 

 action of mesodermal cells is believed to have an important bearing upon 

 immunity and recovery from infectious diseases (see pp. 172 and 181). 



1 These giant cells may be formed either by the fusing together of endothelial or 

 connective-tissue cells, or by a division of nuclei and increase in the cytoplasm of con 

 nective-tissue cells, without a further division of the body. The possibilit}' must be 

 recognized that giant cells may be formed also by the fusion of leucocytes. Giant 

 cells are frequently present in granulation tissue which is forming simultaneously with 

 the absorption of some foreign substance or considerable quantities of dead tissue (Fig. 

 44). For a study of giant cells, with bibliography, consult Hektoeit, Jour. Exp. Med., 

 vol. iii., p. 21; Fuerst. Ziegler's Beitriige, Bd. xxiv., p. 440; and Buxton, "Studies from 

 Department of Pathology Cornell University," vol. i. 



' 2 For a resume of the action of ferments in pathology see Jacoby, Ceutrbl. f. Path.. 

 Bd. xiii., p. 2. 



FIG. 44. GIANT CELLS. 



The giant cells are at the border of a layer of granulation 

 tissue formed about a mass of dead fibrous tissue which is 

 being absorbed. 



