THE CELLULAR MECHANISMS OF DEFENCE 1025 



wall (according to Arnold this process of emigration always occurs through 

 the stigmata, i.e. the points where the endothelial cells come in contact 

 Fig. 482). The prolongation enlarges on the outer side of the vessel, while 

 the portion of the leucocyte within the vessel becomes smaller, so that finally 



b 



^ 



-, ^ 



FIG. 481. Inflamed mesentery of frog, to show margination of leucocytes in the 

 inflamed capillaries, a ; migration of leucocytes, 6 ; escape of red corpuscles, c ; 

 accumulation of leucocytes outside the capillaries, d. (From ADAMI after 



RlBBERT.) 



the whole leucocyte passes through and lies in the lymph spaces outside 

 the capillary. In the course of five or six hours all the capillaries and small 

 veins in the neighbourhood of the injury may show a crowd of leucocytes 

 along their outer surfaces. The use of this emigration seems to be to re- 

 move the tissue injured by the primary lesion. As soon as this is effected, 



FIG. 482. Emigration of leucocytes through capillary wall. (ARNOLD.) 



regeneration of the injured tissue occurs by a proliferation of the connective- 

 tissue corpuscles and the epithelium, while the leucocytes move away and 

 disappear. The essential phagocytic character of the inflammatory process 

 may be shown if the primary lesion be attended with infection. Thus if a 

 small quantity of the staphylococcus be injected into the subcutaneous tissue 

 of the rabbit, the vessels surrounding the point of injection within four hours 

 may be found densely filled with corpuscles. In ten hours' time the leuco- 

 cytes are present in large numbers outside the vessels, while the injected 

 cocci have spread for some distance along the lymphatic spaces and, while 

 partly free, have been to a large extent ingested by the leucocytes. In 



33 



