BY R, GREIG-SMITH. 



569 



COCCUS pyogenes albus, the other Staph, pyogenes aureus. These 

 races were compared with the race which had been used through- 

 out these experiments under the name of Micr. aureus (Mig.). 

 In testing the agglutinative power, the serum was used in 

 dilutions varying from 1-10 to 1-100. 



Agglutination and Opsonisation of three races of Staphylococcus. 



The experiment shows that a weak agglutination may be 

 accompanied by a weak opsonisation, but when time is given for 

 the bacteria to produce a greater quantity of agglutinable sub- 

 stance, the agglutination becomes stronger and at the same time 

 the opsonic power is increased. 



The investigation has shown that the opsonins and agglutinins 

 are probably identical, inasmuch as they have many points of 

 similarity, and probably no points of difference. The similarities 

 are as follows : — 



1. Staphylococcus opsonin and agglutinin are not destroyed 

 at 60°; their powers are only temporarily in abeyance. Contact 

 with the bacteria for 20 hours induces a recovery. 



2. In dilute saline solutions the recovery of the opsonic power 

 is accompanied by an agglutination of the bacteria. 



3. Potassium chloride gives a greater agglutinative and a 

 greater opsonic effect than sodium chloride. 



4. Dilution of the serum with saline solutions increases the 

 agglutinative and the relative opsonic effects. 



5. Longer cultivation of a weak race of staphylococcus increases 

 the agglutinability and the opsonisation of the cells. 



Opsonisation appears to be the first phase of agglutination. 



