1905.] On the Opsonic Action of the Blood Serum. 383 



inhibit the agglutination, although the agglutinin is apparently not 

 entirely destroyed. In comparison with the lysins and agglutinins the 

 antitoxins are believed to be relatively simple bodies. We have asked 

 ourselves the question to which, if any, of these classes do the opsonins 

 belong, and we have followed the usual methods of experimentation 

 which have been utilised to determine the constitution of such anti- 

 bodies. These experiments chiefly consist in determining the tempera- 

 ture at which the specific action is abolished, the temperatures at which 

 the antibody enters into combination with the bacteria, and whether the 

 action of heat is one of destruction or merely a conversion into some 

 modification in which the specific action is no longer manifest. 



Can the opsonin act on bacteria which have been subjected to high 

 temperatures 1 



Experiment 1. 



Technique. Emulsions of cultures of staphylococcus were placed 

 in sealed glass tubes and subjected to temperatures of 100 to 134 C. 

 for varying periods, the opsonic action of serum on such heated cultures 

 being compared with that upon unheated emulsions. 



Results. 



Cocci per 

 leucocyte. 



1. Normal human serum + unheated cocci + leucocytes = 30 



2. + cocci heated to 100 C. for 30' + =20 



3. + ., 100 C. for 60'+ =20 

 4" + 115 C. for 30'+ = 15 

 5. + 120C. for 30'+ - 15 



Experiment 2. 



Cocci per 

 leucocyte. 



1. Human serum + unheated cocci + corpuscles = 27 



2. + cocci heated to 100 C. for $ hr. + 



3. + 1 + - 15 



4. + Hbrs. + =12-9 



5. + 2* + =13 



6. , + 134 C. for 1* =12-6 



From these experiments it is apparent that there is a certain falling- 

 off of the opsonic action when the cultures are kept at high tempera- 

 tures for long periods, but even at 134 C. for 1J hours the diminution 

 in phagocytic power is about 50 per cent. It is possible, too, that the 

 readings are really higher, as it is often very difficult to count the 

 bacteria which have been subjected to such high temperatures on account 

 of defective penetration of the stains employed. 



Effect of heating to 60 C. a mixture of serum and cocci which have 



already been digested at 37 C. for 15'. 



2 F 2 



