BY R. GREIG-SMITH. 



563 



been done, and emphasise the correspondence of opsonisation and 

 agglutination. The citrated serum showed a certain opsonic 

 effect within half-an-hour, but when the time of contact with the 

 bacteria was increased, the agglutinative effect became manifest 

 and simultaneously the opsonic effect was enhanced. 



In the experiments with the diluted serum, it was curious that 

 while normal serum had a phagocytic index of 25, the same 

 serum, diluted to one-fifth, instead of an index of 5 had that of 

 31. The phagocytosis with the dilute serum was relatively six 

 times greater than with the undiluted. This was also found by 

 Wright and Douglas in experiments with unheated serum diluted 

 with heated serum and with normal saline. In their experiments 

 a three-fold dilution of serum increased the opsonic effect to a 

 maximum. In the following, the same result was obtained. 



The effect of diluting norbial serum. 



It is known that in flocculation generally, potassium salts are 

 more active than those of sodium. In the special case of agglu- 

 tination, Friedberger* showed that the same law held, and Joosf 

 admitted that suspensions of Bad. typhi were rather more slowly 

 agglutinated by sodium chloride than by potassium or ammonium 

 chlorides. 



In three experiments with living staphylococci, opsonisation 

 was more pronounced when potassium chloride was used in 

 making the dilutions, the bacterial and the corpuscular suspen- 

 sions. 



* Cent. f. Bakt. i. xxx. 342(table). 

 t Cent. f. Bakt. i. xxx. 857. 



