
1905.| Substance in Serum which influences Phagocytosis. 517 
A number of experiments were carried out with the view of ascertaining 
the relation of the substance in normal serum to the substance in immune 
serum.. 
Experiment to ascertain whether Cocci fully occupied by the Substance from Normal Serum 
are capable of absorbing the Substance from Immune Serum. 
An emulsion of Staphylococcus, prepared in the usual manner, was added to normal 
horse serum which had been heated for 25 minutes to 60° C. The mixture was placed at 
37° C. for 15 minutes, and the cocci were then centrifugalised till all were removed from 
the fluid. The supernatant fluid was then removed and the cocci rapidly washed with 
normal salt solution and again thrown down, great care being taken to avoid any loss of 
the cocci during the process. 
To equal parts of a certain Staphylococcus immune serum from the horse, also feared to 
60° C. for 20 minutes, there were added equal parts of the sensitised cocci and of fresh 
normal cocci. These mixtures were then centrifugalised, and the phagocytic indices of the 
supernatant fluids estimated and compared, the usual proportions of washed leucocytes and 
Staphylococcus emulsion being used. 
Cocci counted in 
22 leucocytes. 
No. of ingested 
cocci per leucocyte. 
Oxieinal)| Weated MMMUNES SCTUM 12 .:5....6.00cdcscecgoeesddsoesdoncecesoessedevnse 24 
Original heated immune serum through which prepared cocci had 
Me CRMC MUNI UMS OC hoes sc sajceacesdae.tidnaleonte tanie Sue ogy seeennaaecuceds seasaecean’ 13 
Original heated immune serum through which nurmal cocci had been 
Ce CMLUPUIMTO DUS Warmer vec a.c5s- stoned seas Sa. Asem Cue Sacre e Oe roe ee aanstes rs 4 
These numbers are the mean of three counts each of 22 polymorphonuclear leucocytes. 
A similar experiment carried out with a dilution of one in five of a similar serum of 
greater potency gave the following numbers :— 
Cocci counted in 
22 leucocytes. 
No. of ingested 
cocci per leucocyte. 
Phagocytic index of the dilution of original Staphylococcic immune 
SERBUTIEO POMONSOy ovat oct clntna scdaneias ato sneer eneeh ocd tcacemonn jas sesedascesee' vere 30 
Ditto through which prepared cocci had been passed .................0665 24°3 
3 * normal 5 Pe cc toln ca cce satan 8 
These two experiments seem to show that the cocci occupied by the 
substance from normal serum are incapable of taking up the substance from 
immune serum, whereas fresh cocci are capable of removing a large proportion 
of the substance. 
The converse experiment was carried out. In this case the cocci were first 
prepared by contact with immune serum and then passed through a normal 
serum. For convenience of estimation by Wright’s method, instead of a 
normal heated serum a normal fresh unheated serum was employed. 
Equal measured quantities of fresh cocci and of cocci prepared as in the previous 
experiments by contact with heated immune serum of the horse were added to equal 
