AMEBOID MOT/OX OF LEUCOCYTES 271 



some extent by oil di-oplcts. liiitsdili considered that tlie cleavajic 

 furrow of dividino: cells represented an area of grreater surface ten- 

 sion, and iMcClendon imitated cell division as follows: He suspended 

 a drop of rancid oil and chloroform between water and salt solution, 

 and allowed sodium liydi'ate to floAv from pipettes against two oppo- 

 site points in the droplet, whereon the surface tension was lowered 

 and the drop bulged at these points, the band of higher surface tension 

 constricting the drop between these two points. Burrows states that 

 the changes seen in cells dividing beneath the microscope correspond 

 well to tliese experimental observations.^'*^ 



RELATION OF THE ABOVE EXPERIMENTS TO THE PHENOMENA EX- 

 HIBITED BY LEUCOCYTES IN INFLAMMATION 



The experiments cited indicate strongly, to say the least, that amebse, 

 and presumably leucocytes, react to stimuli of various kinds, chietly 

 through the effect of these stimuli upon surface tension. The stimuli 

 may come from within the cell, being in this case the result of changes 

 in composition brought about by metabolic processes; such chemical 

 products alter the tension of the surface nearest their point of origin, 

 causing what appears to be spontaneous motion. Stimuli acting from 

 without may be chemical, thermal, electrical, or mechanical, but in 

 any event they act as stimuli to motion through their effect upon sur- 

 face tension ; if they decrease the surface tension the cell goes toward 

 them ; if they increase the tension, the cell moves away.^''*' The be- 

 havior of leucocytes in inflammation may be explained on these purely 

 physical grounds very satisfactorily, as follows: 



At the point of cell injury or of infection, substances are produced 

 that exert positive chemotaxis. as can be shown by experiments both 

 outside and inside the body ; these substances are chemotaetic because 

 they influence the surface tension of the leucocytes, and since with 

 most if not all the products of cell disintegration the effect is to lower 

 surface tension, the chemotaetic effect is positive. As the chemotaetic ' 

 substances are produced, they diffuse through the tissues until they 

 reach the walls of a capillary, through which they begin to pass, pre- 

 sumably most rapidly through the thinnest parts of the wall, the 

 '"stomata" and intercellular substance. The leucocytes passing along 

 in the bore of the capillary will be touched by the chemotaetic sub- 

 stances most on the side from which the substances diffuse ; the sur- 

 face tension will be lowered on this side, causing the formation of 

 pseudopodia and motion in this direction. When the leucocytes come 

 in contact with the wall, their surfaces, because saturated with the 

 chemotaetic substances, will have a tension much the same as that 

 of the cells of the capillar^' wall, which are likewise saturated with the 



57a See Trans. Cono;ress Amef. Phys.. 1913 (9), 77. 



57b OH-ions decrease, Il-ions increase the surface tension of leucocytes 

 (Schwyzer, Biochem. Zeit., 1014 (60), 306. 447, 454), which may explain the "fact 

 that lactic and other acids exhibit negative chemotaxis. 



