190 Mr. J. C. G. Ledingham. [Nov. 18, 
coccal emulsion has probably.a great bearing on the rate of fall, especially 
during the upper temperature ranges (vide Experiment VI). A fairly 
constant ratio, however (4—5:1), is found to exist between the degree of 
phagocytosis at 43° C. and that at 18° C. . 
We have now to determine whether this increased phagocytosis following 
rise of temperature is due simply to increased activity on the part of the 
leucocyte. In short, what effect has temperature on the rate of combination 
of the serum with the coccus ? 
To settle this point, a second series of experiments was performed. The 
coccl were sensitised by contact with serum for a fixed time at a certain 
temperature. Thereafter leucocytes were added and incubation performed 
at different temperatures. By this method more or less completely sensitised 
coccl were exposed to the action of the leucocytes. 
Series I. 
Experiment [—A moderately thick emulsion of cocci in normal saline was 
added in equal volume to fresh serum, and kept in contact therewith at a 
temperature of 37° C. for 20 minutes in a small test-tube. One volume of 
leucocytes was then incorporated with one volume of the shaken up and 
partially centrifugalised serum-coccal mixture and incubated at different 
temperatures for 20 minutes. The result was as follows :— 
Temperature. Cocci per leucocyte. 
37° C. 4, *4; 
30 4: °4, 
ily 4 °3 
(The low counts obtained here show that the centrifugalisation of the serum-coccal mixture 
had been carried a little too far.) 
Experiment IJ.—Technique similar Experiment I1I.—Combination at 
to above. 37. C. tor 2 0mmiie: | 
1.2, = 30 aman: 1) = biamane: 
Temperature. Cocci per leucocyte. Temperature. Cocci. 
A1° C, 13 °8 37° C. 12 °5 
37 8 atef 10°3 
30 12-2 
ef, 13 °5 
(Again the fall of temperature had no effect on ’ 
the amount of phagocytosis.) 
Experiment IV.—Combination at 37° C. for 20 mins. 
Lo dibemmist 
Temperature. Cocci per leucocyte. 
37° C, 5°7 
28 
5°2 
18 5°9 
3 °6 
