532 



Dr. W. Bulloch and Mr. G. T. Western. [Feb. 15, 



We have attempted to determine whether the opsonins are specific by 

 experiments of two kinds : — 



1. The first method consisted in estimating the opsonic content of a given 

 serum towards two different bacteria. A suspension of one of these bacteria 

 was digested with the serum, and the mixture was thereafter centrifugalised, 

 the resulting supernatant liquid being tested on both kinds of bacteria. To 

 a quantity of the supernatant liquid the second bacterial suspension was 

 added, and after the lapse of a certain time the centrifuge was again applied, 

 and the resulting liquid was again tested. 



2. The second method consisted in estimating from day to day the opsonic 

 content of the serum of human beings suffering from lupus. At certain 

 periods tubercle or staphylococcus vaccines were inoculated, and the effect 

 on the two opsonic curves was determined. 



1. Experiment on the opsonic action of normal human serum towards 

 Staphylococcus aureus and Bacterium pyocyaneum respectively. 



Normal human serum was mixed with an equal volume of a suspension of 

 Staphylococcus aureus, and the mixture was placed in the incubator for 

 1 hour at 37° C. At the end of this time the mixture was centrifugalised, 

 the supernatant liquid " A" being removed from the deposit of cocci by means 

 of a pipette. The supernatant liquid was in part retained, the remainder 

 being digested for 1 hour at 37° C. with a suspension of Bacterium 

 pyocyaneum , the latter being finally brought down as a deposit in the centri- 

 fuge, leaving a supernatant liquid " B," which was pipetted off. 



Eesult. 



1. Normal serum (1 in 2 dilution) + staphylococci + leucocytes = 22'9" 



2. „ „ (1 in 2 „ ) + B. pyocyaneum + „ = 4/7 



3. „ „ (1 in 4 „ )+ „ + 3-0 



4. Fluid "A" + staphylococcus + 



5. „ "A" +B. pyocyaneum + 



6. „ "B" + „ + 



> u o 



0-5 - 

 4-0 

 0-4 J 



The contact of the serum with staphylococcus leaves the opsonic action of 

 the serum for Bacterium pyocyaneum practically unchanged, the pyocyanic 

 opsonin being finally removed by contact of the serum with this microbe. 



A similar result was obtained when the serum was brought to act on 

 staphylococcus and tubercle bacillus, as can be seen in the following 

 experiment. 



1. Normal human serum was mixed with an equal quantity of an emulsion 

 of tubercle bacilli in - 85 per cent. NaCl solution. The mixture was digested 

 for 30' at 37° C. and then centrifuged. In this way a deposit and a super- 

 natant liquid " A " was obtained. 



