AMEBOID MOTION 2()r) 



that the cytoplasm flowing along its surface cannot surround it; 

 other leucocytes will experience the same change, their cytoplasm will 

 fuse together because of the equal lowering of their surface tension, 

 and soon we got a mass of leucocytes with fused cytoplasm surround- 

 ing the oliject, forming a "foreign body giant-cell." (c) The leuco- 

 cyte may reach a place where the concentration of the chemicals is so 

 great that chemical changes are produced in its cytoplasm. If these 

 changes are of a coagulative nature, the surface of the cell will be 

 stiffened so that it cannot migrate further; if of a solvent nature, the 

 leucocyte is destroyed, (d) It may reach the margin of an area where 

 the preceding leucocytes have become coagulated or otherwise rendered 

 immobile, so that they block its path, while it is held fixed by the at- 

 traction on this side, (c and d explain the formation of solid leu- 

 cocytic walls about areas of inflammation, and the frequent absence 

 of leucocytes within the central necrotic areas.) (e) The formation 

 of chemotactic substances may cease because the substance causing the 

 inflammation has been used up, or because the bacteria have been 

 destroj^ed, or from any of the causes that terminate inflammation. 

 Those leucocytes still advancing will reach a point where there is as 

 much chemotactic substance behind as in front — they will then stop 

 advancing. ^^ As the fluids exuded in the central portion continue to 

 dilute the chemotactic substances and wash them out, there will soon 

 be less chemotactic substance in the center of the inflamed area than 

 there is farther out, hence the leucocytes will move away from the 

 center toward the periphery, following the chemotactic substances 

 back into the blood-vessel and the lymph-stream. These are the 

 conditions that exist at the close of the inflammatory process, which 

 results in the dispersion of the leucocytes. 



General leucocytosis can be explained equally well on the same 

 grounds. Chemotactic substances from the area of inflammation enter 

 the blood-stream, and so, in a very dilute form, pass through the bone- 

 marrow. The chemotaxis in the blood will be greater than that of 

 the marrow, and the leucocytes will move toward and into the blood. 

 As long as the blood contains more chemotactic substances than the 

 marrow, leucocytosis will increase, to stop when the amount in blood 

 and marrow is alike or when there is less in the blood than in the 

 marrow. 



Behavior of Tissue=cens and Formation of Giant=cells. 

 The free cells of the tissues involved in inflammation can, of course, 

 obey the same influences as the leucocytes, and apparently do so in 

 so far as they are not checked by structural impediments to flowing 

 motion; i .e., the more closely a cell is related to a single drop of fluid 



^' The phagocytic action of leucocytes in vitro is decreased by substances that 

 lower the surface tension, e. g. chloroform (Hamburger, K. Akad. Wetensch., 1911 

 (XIII (2)), 892). Ether-soluble substances from bacteria have no effect on 

 phagocytosis (Miiller, Zeit. Immunitat., 1908 (1), 61). 



