266 INFLAMMATION 



protoplasm, the more closely does it resemble in the simplicity of its 

 reactions the "artificial ameba." An illustration of the chemotaxis 

 of epithelial cells is furnished by B. Fischer,^- who found that stained 

 fats cause growth and migration of epithelial cells in the direction of 

 the fat. Cells with much cytoplasm are best fitted to move freely, as 

 a rule, and hence we see chiefly the large endothelial cells of the lymph 

 sinuses and the serous cavities, and the large hyaline and granular 

 cells of the blood acting as phagocytes, for phagocytosis is no different 

 from ameboid motion which continues about a particle until it is sur- 

 rounded; likewise we see the "epithelioid" and large endothelial cells 

 with their abundant cytoplasm fusing together to form giant-cells. 

 (Note that such giant-cells are formed particularly in conditions in 

 which the epithelioid cell is more abundant than is the leucocyte, 

 e. g., tuberculosis and other chronic inflammations. The cells that 

 fuse about an infected catgut ligature are the leucocytes, for they are 

 most abundant in such a place.) A good illustration, also, is the 

 giant-cell formed by fusing of leucocytes about blastomyces in minute 

 abscesses in the epithelium in blastomycetic dermatitis; the epithelial 

 cells cannot flow or coalesce well because of their abundance of stiff 

 keratin and their specialized cell-wall, and hence do not participate; 

 the leucocytes are individually too small to surround the fungus cells, 

 and hence they flow about them in the abscess exactly as they will do 

 experimentally in a test-tube or in a guinea-pig's abdomen (Hektoen). 

 The method of growing tissues in vitro permits of observation of the 

 process of giant-cell formation, and establishes that, for foreign body 

 giant-cells at least, they are formed by fusion of wandering cells 

 (Lambert). ^^ The formation of giant-cells is, on this ground, but an 

 amplification of ameboid movement and phagocytosis. The fusing of 

 the individual cells is due to the lowering of their surface-tension by 

 the materials diffusing from the body which is to be absorbed, until 

 the surface of each cell becomes alike, when the surface tension at 

 the point where each cell is in contact becomes zero and the cytoplasm 

 runs together. 



Objections to the above Hypothesis. — Phj'sical explanations of ameboid 

 movement seem to fit very perfectly the known facts concerning the actions of 

 leucocytes. There arise but a few ditliculties in applying these laws to leucocytic 

 action; one is the phagocytosis of chemically inert bodies, such as coal particles, 

 tattooing materials, stone dust, etc. We know that anioba" al^so may take up such 

 inert materials, altliough tliey generally refuse them, and it is believed that the 

 particles exert some local injury to the cell wall that leads to an alteration in its 

 tension. Ameba; seem also sometimes to excrete a sticky substance over their 

 surfaces or over the foreign nuitter that is to be engulfed, which excretion seems to 

 be the result of surface stimidation. Possibly leucocytes do the same. We nuist 

 bear in mind, however, that the protoplasmic cells luvve much greater possibilities 

 for action than the "artificial ameba," since within the jn'otoplasm countless cliemi- 

 cal changes are going on wliicli nmst cause continual alteration in surfac(> tension; 

 it is quite possible that mere mechanical action nuiy alter cheinica! action at the 



" Miinch. med. Woch., 190G (53), 2041. 

 83 Anatomical Record, 1912 (G), 91. 



