568 IDENTITY OF OPSONINS WITH NORMAL AGGLUTININS, 



Micr. aureus and found that the serum agglutinated the infected 

 race in dilutions of 1-50, while with three other races one gave a 

 characteristic reaction and two did not. 



With regard to the action of normal human serum upon sus- 

 pensions of the staphylococcus, very little has been done. 

 Beitzke* tested 44 specimens of serum, chiefly of corpses. 

 Seventeen of these did not agglutinate when used in dilutions of 

 I-IO. Seven agglutinated in dilutions of 1-50, nine in 1-100, 

 eight in 1-200, and one each in 1-500, 1-1000, 1-2000. He thus 

 found that 61 % of the cases gave a characteristic reaction, and 

 he considered that the agglutination of the staphylococcus by 

 normal human blood was of remarkably frequent occurrence. It 

 may be objected that the blood of cadavers can scarcely be called 

 normal. 



Wrightf examined the blood of four normal men and found 

 that they agglutinated suspensions of the staphylococcus when 

 diluted up to 8- and 16 -fold. 



The experiment on p. 5 64 shows that my own serum when 

 diluted at least 200-fold agglutinated suspensions of the race of 

 staphylococcus that has been used in this investigation. An 

 agglutination in such dilution is undoubtedly characteristic. 



Upon the quantity of agglutinable substance secreted or 

 excreted by the bacterium depends the rapid or slow agglutina- 

 bility with a normal serum. The thinnest film of precipitate, 

 resulting from the reaction between agglutinin and agglutinable 

 substance, will alter the nature of the bacterial surface. From 

 being indifferent to the leucocytes, the bacteria will become posi- 

 tively chemotactic. The flocculating action of the salts, however, 

 may not be sufficiently powerful to cause the thinnest films with 

 the enveloped bacteria to run together into clumps. We can 

 therefore expect to find that races of the staphylococcus while 

 exhibiting a normal opsonisation may be very slowly agglutinated. 

 This was to a certain extent borne out b}'- the examination of 

 two races which 1 obtained from Dr. Tidswell, one of Staphylo- 



* Cent, f. Bakt. (Ref.) xxxv. 709. 

 t Lancet, 29th March, 1902, p.874. 



