1905.] On the Opsonic Action of the Stood Serum. 385 



Experiment. 



Technique. Normal serum mixed with an equal volume of staphylo- 

 coccus emulsion and then filled into a series of capsules. The capsules 

 were sealed and placed in the water bath at 37 C. or in a mixture of 

 ice and salt. After varying periods the capsules were removed and 

 carefully centrifugalised for 1 hour, the clear supernatant fluid from 

 each capsule being tested upon a fresh suspension of staphylococcus to 

 see whether the opsonin had disappeared. As a control the opsonic 

 power of normal serum in proper dilution is also added, likewise the 

 opsonic power of serum which has been heated to 60 C. for 15'. 

 Results. 



Cocci per 

 leucocyte. 

 1. (Control). Normal serum (3 parts) + cocci (1 part) + corpuscles (3 parts) = 18 '7 



2. (Control). Heated 



3. Supernatant fluid from capsule 



at 37 C. for 5' + 



4. Ditto ditto ditto 10' + 



5. Ditto ditto ditto 15' + 



6. Ditto ditto ditto 30' + 



7. Ditto ditto ditto 45' + 



8. Ditto ditto at C. for 10' + 



9. Ditto ditto 20' + 



10. Ditto ditto 30' + 



11. Ditto ditto 45' + 



= 0-1 



- 



= 



= 



= 



= 



= 



= 



= 



= 



The result is unequivocal ; the opsonin had completely disappeared 

 from the serum within 10' both at 37 C. and at C. 



Experiments to Determine the Nature of the Opsonic Body, and its Mode 

 of Action. We have seen above, that when heated to 60 C., serum 

 ceases to exert an opsonic effect. We have also seen that opsonin 

 disappears from the serum when the latter is digested with bacteria at 

 37 C., or at C. Is this disappearance due to destruction, or does 

 the opsonin pass into some modification, in which an opsonic effect is 

 not visible 1 Is the opsonin a simple, or a complex structure 1 



Experiment. 



Technique. (I) Normal serum was digested with an equal quantity 

 of emulsion of cocci at 37 C. for 15'. After digestion, mixture was 

 centrifugalised for f hour. In this way a clear supernatant fluid (A) 

 was separated from a deposit of cocci (A'). 



(2) Normal serum was digested with an equal quantity of emulsion 

 of cocci at C. for 15', centrifugalised as above, and separated into a 

 supernatant fluid (B) and a deposit (B'). 



As the serum was mixed with equal quantity of cocci, the controls 

 made with normal serum and " normal " cocci are given in their appro- 

 priate dilutions, which were made with 0-85 per cent, saline. The term 

 " normal " is applied to cocci which have not been treated in any way. 



