194 Mr. J. C. G. Ledingham. [Nov. 18, 
Experiment XIV. 
Period of combination, 1 hr. 45 mins. 
Bacilli per leucocyte. 
Supernatant fluid after combination at 37° C. ......... 1-4 
” ” a 0° C. EG OTe 5:1 
Fresh: S@num, «1: wisieaits itaieee en cee acne oe me was eee oa 
These were the figures obtained after phagocytosis for 15 minutes. When 
phagocytosis was prolonged to 30 minutes the corresponding values obtained 
were 1:6, 11:3 and 10:9. The supernatant fluid, after combination at 37° C., 
had therefore been exhausted of its available opsonin after 15 minutes, 
whereas in the case of the second supernatant fluid (combination at 0° C.), the 
prolongation of the incubation period from 15 minutes to 30 minutes had 
the effect of more than doubling the phagocyticintake. Further, these fluids 
were tested against a fresh emulsion of staphylococci, when the following 
figures were obtained :— 
0-9, 32, and 4:0 (control serum). 
After combination at 37° C., therefore, the serum had lost nearly all its 
contents of tubercular and staphylococcal opsonins, whereas, after absorp- 
tion at 0° C. little loss had occurred. It may be noted that incidentally the 
result tells against the specificity of the opsonin of normal serum. 
There can be no doubt that absorption at 37° C. removes from a serum far 
more opsonin in the same time than absorption at 0° C. does. An attempt 
was made to test the degree of sensitisation of the centrifugalised bacilli 
after combination at 37° C. and 0° C. respectively. The supernatant fluids 
were removed and replaced by saline (twice repeated). When leucocytes were 
added to saline emulsions of the deposited bacili, made up to the same 
volume and incubated at 37° C., little difference was found in the numbers 
taken up in the two cases. The technique is difficult and further experi- 
ments may have to be performed in this connexion, but if the phenomenon 
is constant it would show that at 37° C. the bacilli absorb more opsonin than 
is necessary for efficient sensitisation, while at 0° C. the bacilli remove just 
sufficient opsonin to prepare them for phagocytosis. 
Summary and Conclusions. 
1. When serum, cocci, and leucocytes are mixed directly and incubated at 
different temperatures, the number of cocci taken up increases more or 
less regularly with. the temperature. By this method it has been shown 
that the phagocytic intake at 18° C. is only about one-fourth to one-fifth of 
that at 37° .C. 
