WALLACE O. FENN 



341 



large, the general tendency for ^lo to increase at lower temperatures 

 is perfectly clean-cut. 



The simplest interpretation of these results seems to be that at the 

 lower temperatures the cells are actually too rigid to permit either the 

 sticking on of the particles or the relatively greater changes in form 

 which are necessary for ingestion. A slight increase in temperature 

 now sufhces to transform the protoplasm possibly from the gel to the 



TABLE II. 



Temperature Coefficient of Phagocytosis of Solid Particles. 



Comparisons were made at three different stages of the reaction; i. e., when 

 25, 50, and 75 per cent of the particles had been ingested. In Experiments 1, 4, 

 and 7, Qio was measured from 27°C. to 37°C. 



sol stage, thereby rapidly increasing the rate of phagocytosis; i.e., 

 Qio is high. The low temperature coefficient above 30°C. might be 

 taken to indicate that phagocytosis is merely a matter of surface 

 tension changes. But this conclusion is not justified since many of 

 the particles were merely stuck on the outside of the leucocytes singly 

 or in clumps, making impossible any conclusion as to the temperature 

 coefiicient of the actual process of ingestion. The fact that no 

 appreciable clumping occurs at lower temperatures shows that the 



