1907.] The Influence of Temperature on Phagocytosis. 193 
the degree of phagocytosis is independent of the temperature within the 
range 37° C—18° C. Further, when we compare the figures in the two series, 
those of the right hand series (combination at 18° C.) decidedly lag behind 
those of the left hand series (combination at 37° C.). The difference, 
however, is not nearly so marked as in a previous experiment, where the 
effects of combination’ at 37° C. and 7° C. were compared. One point is 
somewhat difficult to explain. In the case of combination at 18° C. it was. 
found in an earlier experiment’ where thick emulsions were’ employed that 
the amount of phagocytosis at 18° C. fell considerably below that at 37° C. 
In the present experiment, where thin emulsions were employed for combin- 
ing purposes, these values are equalised. The reason probably is that, 
although the rate of combination at 18° C. is slower than that at 37° C., 
prolonged contact of serum with cocci at the lower temperature (18° C.) 
effects a maximum absorption of opsonin by the cocci for that temperature, 
and, consequently, when phagocytosis takes place, the influence of temperature 
within the range 37° C.—18° C. is reduced toa minimum, just as in the case of 
combination at 37° C. Ina paper by Bulloch and Atkin (1905) it is stated 
that the combination of the opsonin with the micro-organism takes place as 
readily at 0° C. as at 37° C. If this were so, it would be difficult to explain 
many of the experimental results detailed above. Dean (1905), on the 
contrary, observed that combination at 0° C. was much slower than at 37° C. 
The problem was again attacked in the following way :— 
Experiment XIJ.— Emulsions of dead tubercle bacilli were incorporated with 
equal volumes of serum at the temperatures of 37° C. and 0° C. for a period of 
30 minutes. The mixtures were then completely centrifugalised and the 
opsonic contents of the supernatant fluids towards fresh tubercle bacilli 
compared, fresh normal serum, in corresponding dilution, being employed a 
control. | 
Bacilli per leucocyte. 
Supernatant fluid after combination at 37° C. ......... 3°4 
. Me 5) ig, Oe 6-4 
kinesin serum (diluted). 0..fsis tase cis ag ae ke ds 6°2 
Experiment XIII. 
Here the period of combination was prolonged for 11 hours. 
Bacilli per leucocyte. 
Supernatant fluid after combination at 37°.C. ......... 2°5 
” » ” 0° C. Deororteerelene 6°7 
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