1907.] Substance in Serum which influences Phagocytosis. 411" 



1. Normal rabbit's serum, heated to 60° C. for 20 minutes, 1 volume, + 

 Immune rabbit's staphylococcus serum, heated to 60° 0. for 20 minutes, 



1 volume, + 

 Normal human serum, fresh (dilution 1 : 10), 1 volume, + 

 Leucocytes, 1 volume, + 

 Cocci, 1 volume 



2. Normal rabbit's serum, heated to 60° C. for 20 minutes, 1 volume, + 

 Normal salt solution, 1 volume, + 



Normal human serum, fresh (dilution 1 : 10), 1 volume, + 



Leucocytes, 1 volume, + 



Cocci, 1 volume. , 



3. Normal rabbit's serum, heated to 60° C. for 20 minutes, 1 volume, + 

 Immune rabbit's staphylococcus serum, 1 volume, + 



Normal salt solution, 1 volume, + 

 Leucocytes, 1 volume, + 

 Cocci, 1 volume. 



4. Anti-complement rabbit's serum, heated to 60° C. for 20 minutes, ] volume, + 

 Immune rabbit's staphylococcus serum, heated to 60° C. for 20 minutes, 



1 volume, + 

 Normal human serum, fresh (dilution 1 : 10), 1 volume, + 

 Leucocytes, 1 volume, + 

 Cocci, 1 volume. 



5. Anti-complement rabbit's serum, heated to 60° C. for 20 minutes, 1 volume, + 

 Normal salt solution, 1 volume, + 



Normal human serum, fresh (dilution 1 : 10), 1 volume, + 

 Leucocytes, 1 volume, + 

 Cocci, 1 volume. 



6. Anti-complement rabbit's serum, heated to 60° C. for 20 minutes, 1 volume, + 

 Immune rabbit's staphylococcus serum, heated to 60° C. for 20 minutes, 



1 volume, + 

 Normal salt solution, 1 volume, + 

 Leucocytes, 1 volume, + 

 Cocci, 1 volume. 



Phagocytic 

 index. 



Y 15-1 



6-9 



3-0 



2 4 



Y 1-7 



J 



3 7 



Summary. 



1. Dilution of fresh unheated serum is not accompanied, so far as the higher 

 concentrations are concerned, by a fall in the sensitising power for certain 

 organisms (staphylococcus, tubercle bacillus). The diminution in this was 

 found, as a rule, to begin at the quarter concentration. 



2. So far as the present experiments go, the points corresponding to the 

 l/4th, l/8th, l/16th, and l/32nd dilutions of normal human serum lie on 

 a parabola whose equation is y 2 = 4X, i.e., for these dilutions the phago- 

 cytosis is proportional to the square root of the serum concentration. 



3. The phagocytic index obtained by mixing appropriate dilutions of 

 a heated immune serum with a normal fresh serum is greater than results* 

 from the two substances acting separately. 



