WALLACE O. FENN 



343 



results of Madsen and Watabiki. Similar indications are found, 

 however, in measurements of the temperature coefficient of the 

 ameboid motion of leucocytes by Commandon (7) who took moving 

 pictures of creeping leucocytes at 25°, 30°, and 35°C. and deter- 

 mined the rates of movement by subsequent measurements on the 

 films. He gives the following figures: 



From these figures the Qiq has been calculated as described and was 

 found to be 4.6 between 25° and 30°C., and 1.5 between 30° and 35°C. 

 Similar evidence of a rapid change in the temperature coefficient 

 of ameboid movement below 30°C. was found in some preliminary 

 experiments designed to measure the effect of temperature on phago- 

 cytosis by the "film method," previously described (2). In this 

 method the leucocytes and particles are allowed to settle out between 

 a slide and cover-slip in a thin film and the rate of phagocytosis is 

 measured by counting the number of particles not yet ingested over 

 equal areas. It is impossible to be sure, however, whether this rate 

 is determined by the speed with which the leucocytes creep about 

 from particle to particle or by the actual ease of ingestion. Demon- 

 strations by this method, of the more rapid ingestion of carbon parti- 

 cles as compared with quartz, have shown that in this case at least 

 the speed of the leucocytes is not the limiting factor. However that 

 may be, the temperature coefficients of phagocytosis as measured by 

 this method show the same marked increase at lower temperatures. 

 This is shown in Table III. 



