342 TEMPERATURE COEFFICIENT OF PHAGOCYTOSIS 



clumping is due to the increased stickiness or phagocytic activity of 

 the cells. 



In this connection the parallel fact is significant that the presence 

 of solid particles has been found (2) to cause more rapid clumping of 

 the leucocytes. Thus, at the optimum temperature for phagocytosis 

 there is both an agglutination of cells due to particles and an agglutina- 

 tion of particles due to cells. The complete act of phagocytosis is 



Per cent 

 Particles Tree 



80 MJn. 



Fig. 5. Curves showing the number of particles of carbon still free (ordinates), 

 i.e., not ingested by leucocytes, as a function of time (abscissae), at 23°, 27°, and 

 37°C. Inspection shows that the temperature coefficient is greater between 23° 

 and 27°C. than between 27° and 37°C. See Table I for figures from this and other 

 similar experiments. 



evidently a complex of several reactions, and any figure which may be 

 obtained for the temperature coefficient of the process must be 

 interpreted from this point of view. The fact that Qio is not constant 

 must mean that new reactions become the limiting factors as the 

 temperature changes. Below 30°C. the fluidity of the cell is the 

 limiting factor. Above 30°C, it is the stickiness of the cells which 

 would be expected to vary merely with the surface tension. 



These results indicate then a marked change in the consistency of 

 the protoplasm between 20° and 30°C. which did not appear in the 



