272 INFLAMMATION, REGENERATION, GROWTH 



same substances, and the two surfaces will tend to cling to one another ; 

 explaining the phenomenon of adhesion of leucocytes to the capillary 

 wall, when, according to the usual description, ''the leucocytes be- 

 have as if either they or the capillary wall had become sticky. ' ' ^® Sur- 

 face tension of the leucocytes will be least nearest the points where the 

 most chemotactic substances are entering the capillary, namely, the 

 stomata; hence the pseudopodia will form in this direction and flow 

 through the openings, the rest of the cytoplasm flowing after and 

 dragging the nucleus along in an apparently passive manner. Since 

 it is the cytoplasm that seems to be chiefly affected in these processes, 

 the nucleus appearing to be rendered inert by its relatively dense and 

 fixed structure, the leucocytes with most cytoplasm are most active in 

 emigration, while those with the least, the lymphocytes, are affected 

 relatively little or not at all. 



Once through the vessel wall, the motion continues in the same 

 manner, toward the side from which the chemotactic matter comes, 

 just as the mercury drop flows toward the crystal of potassium dichro- 

 mate, or the drop of oil flows toward the alcohol. If the leucocyte 

 meets a substance that lowers its surface tension sufficiently, it will 

 flow around the object and enclose it, just as the chloroform drop 

 flows about the piece of shellac or balsam; this constitutes phago- 

 cytosis. The motion of the leucocyte will continue in a forward di- 

 rection until one of several possible things happens : (a) The leucocyte 

 may reach a point where the chemotactic substances are so thoroughly 

 diffused that the effects on its surface are the same on all sides; 

 there will then be no tendency to move in any direction, (h) It may 

 reach a material that exerts a marked positive influence upon it, 

 causing much lowering of the surface tension, but which is so large 

 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 get a mass of leucocytes with fused cytoplasm surround- 

 ing the object, 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 



«8 Kreibich (Arch. f. Dermatol., 1012 (114). 585) describes as chemical chanpes 

 in the vessel walls fhirinjr the early stages of inflammation, a difTuse siulanonhile 

 ehanpe throntrhoiit the endothelial cells, in the form of fine, dust -like particles. 

 Probably this chancre dejjcnds .simply on an atrurefratio!! of the iiitrat'cllnlar 

 lipoids. 



