1907.) The Influence of Temperature on Phagocytosis. 195 
2. This fall, at least within the temperature range 37° C.—18° C., is due 
‘to the diminished rate of combination of the serum with the coccus as the 
‘temperature falls. : 
3. When cocci which have previously been exposed to the action of serum, 
either at 37° C. or at 18° C., are put in contact with leucocytes, the intake 
is practically the same whether the phagocytosis takes place at 37° C. or 
at 18° C. The number taken up, however, after combination at 18° C. and 
‘more especially at 7° C., falls very short of the number taken up after 
combination at 37° C. 
4. Experimental results, detailed above, lead one to assume that pro- 
longed contact of a serum with cocci at a low temperature (18° C. or 7° C.) 
leads to a maximum absorption of opsonin by the cocci (corresponding to 
that temperature), so that the subsequent phagocytosis is identical 
whether it takes place at 37° C. or at 18°C. 
5. Provided that cocci loaded with opsonin up to a certain maximum 
are presented to the leucocyte, the phagocytic energy of the latter is 
independent of the temperature within a wide range. 
6. From the appearances on stained films it would seerh that 
‘sensitised micro-organisms exposed to the action of leucocytes at very low 
temperatures tend to congregate near the periphery of the leucocytes, 
although little or no phagocytosis may take place. Hence, within a suit- 
able temperature range, it may be presumed ‘that the inclusion of 
sensitised micro-organisms by the leucocyte is a surface tension effect | 
taking place between the coccus and the protoplasmic wall, amceboid energy 
playing only a subordinate part in the process. 
REFERENCES. 
Bulloch and Atkin, ‘ Roy. Soc. Proc.,’ vol. 74. 
Dean, G., ‘Roy. Soc. Proc.,’ B, vol. 76. 
