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OPSONISATION FROM A BACTERIAL POINT OF 

 VIEW AND OPSONIC TECHNIQUE. 



By R. Greig-Smith, D.Sc., Macleay Bacteriologist to the 



Society. 



When this research with Micrococcus aureus was begun, about 

 two years ago, the tendency of opsonic investigation had been 

 chiefly in the direction of the opsonic content of serum, and little 

 had been done from the point of view of the bacterium and its 

 environment. It appeared that much might be gained by regard- 

 ing opsonisation from this aspect, especially as bacteria are infer- 

 entially considered to form or secrete an opsonisable substance. 

 Variations in the formation of this body should be shown in an 

 increased or decreased opsonisation of the bacteria. The measure 

 of the formation will be shown by the extent to which the 

 bacteria are ingested by the phagocytes, and especially by the 

 polymorphonuclear leucocytes of the blood after treatment with 

 opsonin-containing serum. As the research proceeded, questions 

 regarding the technique of the process arose, and the scope of 

 the investigation broadened. 



The virulence of young cultures. — In the action of opsonic 

 serum upon bacteria, we might obtain an explanation for the 

 virulence of young as compared with older cultures of bacteria, 

 especially if we take into account the remaining feature of the 

 total phenomenon of which opsonisation is the first and phago- 

 cytosis the second step. The ingestion of the bacteria, although 

 undoubtedly a great advance towards their destruction, need not 

 necessarily mean that they are rendered less virulent. Indeed 

 phagocytosis might make bacteria more deadly by conveying them 

 to distant and more vulnerable parts of the animal. If an 

 increased opsonisation is going to enable us to understand the 

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