PlIACOCYTOf^IS 263 



])luifjoc'ytes is aseribod by Rhuinbler tu changes in tlic eoiuixjsitiuu of 

 the''l)artick's through digcstioii, so that they have a greater surface 

 affinity for the surrounding fluids than for the protoplasm of the cell. 

 Calcium and magnesium salts increase phagocytosis and leucocytic 

 migration/" while changes in osmotic pressure decrease these activi- 

 ties, as also does (luinine even in dilutions of 0.001 per cent. Phago- 

 cytosis cannot take place in the absence of electrolytes, according to 

 Sawtchenko.'^ Fat-soluble substances in general increase phagocyto- 

 sis (Hamburger),*''^ but cholesterol inhibits phagocytosis,""^ (its ef- 

 fects being suppressed by lecithin) *'' acting apparently by virtue of 

 its OH group. Agents facilitating oxidation favor phagocytosis 



(Arkin)."'' 



Phagocytosis cannot be readily a.scribed to chemotaxis, however, 

 in the case of phagocytosis of perfectly insoluble, chemically inert par- 

 ticles, such as coal-dust. The leucocytes seem to take up foreign bod- 

 ies without reference to their nutritive value, absorbing India-ink 

 granules and bacteria impartially when they are injected together, 

 and loading themselves so full of carmine granules that they cannot 

 take up bacteria subsequently injected. It is possible that foreign 

 bodies first become coated with a" layer of altered protein which then 

 leads to phagocytosis, but there is no sufficient evidence for this sur- 

 mise. Kite and Wherry "« state that leucocytes take up carbon parti- 

 cles and similar substances because the leucocytes are "sticky," which 

 presumably is correct, but what constitutes the "stickiness" and why 

 it varies under the influence of serum is not indicated. Presumably 

 it represents an altered viscosity, which is known to be increased by 

 increased acid content such as might be produced by local asphyxia."*'' 

 The nature of mechanical stimulation of cells is explained by Oster- 

 hout"^ as a chemical reaction to rupture of semipermeable cellular 

 surfaces, and there is evidence from plant cells supporting this hy- 

 pothesis, but its applicability to animal cells has not been investigated. 

 The experiments of Schaeffer "^ seem to show that ameba^ exhibit 

 positive chemotaxis towards such insoluble substances as carbon parti- 

 cles and glass fragments, even at a distance, although the mechanism 

 is unexplained. Similar investigations have not been made with 

 leucocvtes. 



Not only leucocytes but tissue cells are capable of moving and per- 



40 Hamburger, Biochem. Zeit., 1010 (2G), 66; Eggers, .Tour. Infect. Diseases, 



^'^I'^Ardi". S'biol. St. Petersburg, mil (10), 161 ; .Ifl^ HJ) • 128. 



4ia Ilanil.urger and de Haan. Arcli. Anat. und Physiol._. 1913, Phys. AM., p. ,,. 



41b Dewev and Xu/Aim, .Tour. Tnfect. Dis , 1014 (1.5), 472. 



4ieStuber. Biochem. Zeit., 1013 (51), 211; 1014 (53), 493. 



4id Jour. Infect. Dis.. 1013 (13), 418. 



4ieJour. Infect. Dis., 1915 (16). 109. 



4ifSee Woolley, Jour. Amer. Med. Assoc, 1914 (63), 22/9. 



4igProc. Natl.' Acad. Sci., 1916 (2), 237. 



4ihBiol. Bull., 1916 (31), 303. 



