516 Mr. G. Dean. On the Nature of the — [July 8, 
Cocci counted in 
22 leucocytes. 
No. of ingested 
Vol. —_— cocci per leucocyte. 
Coccal emulsion which had been kept at 37°C. 1 99 
+ Ehumans leucocytes), s25is.eeses taedeseessnna. eee il 
Coccal emulsion which had been kept at6—8°C. 1 99 
+ Human leucocytes ..20...¢srsees.- +022 -oouce nee 1 
This experiment seems to show that the substance acts on or becomes 
attached to the cocci much more slowly at low than at high temperatures. 
Microbes which have been placed in Contact with Immune Serum are capable 
of taking up an Excess of the Substance which can again Diffuse into the 
Surrounding Fluid. 
05 cc. of an emulsion of Staphylococcus was put in contact with 2 c.c. of a heated 
immune serum and left in contact at 37° C. for 1 hour. The cocci were then separated 
by centrifugalisation, washed and put into 1 c.c. of an immune serum, X, and left in 
contact for an hour at 37° C., then centrifugalised very carefully so that all the cocci 
were thrown down. 
Cocci counted in 
22 leucocytes. 
No. of ingested 
Vol. cocci per leucocyte. 
‘Fresh: serum © 2X77 007, caste seco one ere nee 1 
-+- Staphylococcic-emulsion 72. .72.2.. .0---seyacceaen-- ee 1 } 37 
+ Washed horse leucocytes.............ccrersessseseeees il! 
Serum, X, through which prepared cocci have 
been centrifugaliseds 2, we ecee corneas i 
+ Stapnylococeie.omimlStOnuss:o2..cuee-e seco eeee eee 1 f 48 
+ Washed horse leucocytes...............0cecscsececeees 1 
This points to a diffusion of the substance into the serum from the cocci. 
Experiment.— Cocci which had been treated, as in the previous experiment, with immune 
serum, after being centrifugalised and rapidly washed with normal salt solution, were 
left in contact for 24 hours with normal salt solution, which was then tested for the 
presence of “ opsonin.” 
Cocci counted in 
22 leucocytes. 
No. of ingested 
Vol. cocci per leucocyte. 
Washed leucocytes of horse .............2:.0ce0c0es 1 0-5 
+Nonmal salt solution ii2o22.us.w22-2-- enero 
1 
Washed leucocytes'of horse ..................00000 a 2] 
+ Normal salt solution, from above prepared cocci 1 
