106 CAN OPSONINS BE OBTAINED DIRECTLY FROM BACTERIA, ETC., 



In an attempt to detect the liberation of opsonin from bacteria 

 under the influence of pepsin-hydrochloric acid, ferric chloride 

 was added to assist digestion. Experiments had shown that a 

 greater loss of staining power as indicated by the Gram method 

 of staining was obtained when to the pepsin-hydrochloric acid, 

 salts of iron, calcium, barium, nickel or aluminium had been 

 added, and of these salts ferric chloride appeared to be most 

 active. 



The results of a great number of experiments made with yeast 

 and with Staphylococcus aureus which in some cases had been 

 heated in saline at 60'^ for an hour, showed that no opsonin was 

 liberated. The bacteria, either when heated or not, continued 

 to give off anti-opsonic bodies for a considerable time. 



In experiments such as these it is necessary to have the 

 digested extracts absolutely free from bacterial cells. This con- 

 dition was not always obtained upon neutralising the acid ferric 

 chloride with sodium carbonate as the precipitate of ferric 

 hydrate api)eared to be too rapidly formed to entangle all the 

 bacterial cells, and an apparently brilliant fluid contained enough 

 cells to vitiate the results. A clear and trustworthy fluid was 

 obtained by treating the first clear extract, freed from iron, with 

 calcium chloride and phosphoric acid and neutralising with 

 sodium carbonate. The precipitate of calcium phosphate is 

 formed slowly and entangles all the partly digested bacteria. 



Subsequent treatment of the bacteria with pancreatic extract 

 (liquid pancreatin from Parke, Davis <fe Co.) in faintly alkaline 

 solution or in 0-2% Na2C03 also gave negative results. 



Yeast-extract as obtained by grinding up yeast with sand and 

 extracting the mass with a small quantity of saline also showed 

 no trace of opsonin. 



It is concluded from the research that opsonins are not 

 directly obtainable from either bacteria or yeast. 



