240 BIOLOGY OF PNEUMOCOCCUS 



cultures of Pneumococcus of Types I, II, and III, in human blood 

 serum, in urine during the course of lobar pneumonia* and, at 

 times, in the blood of experimentally infected animals, a soluble 

 substance that gave a specific precipitate with antipneumococcic 

 serum of the homologous type. According to the authors, the sub- 

 stance was present in cultures when the organisms were growing at 

 maximal rate and undergoing little or no cell death. Consequently 

 its presence was not dependent upon cell disintegration, but repre- 

 sented the extrusion of bacterial substance by the living organism. 

 The substance was readily soluble in water, was not destroyed by 

 boiling, was not digested by trypsin or urease, did not dialyze 

 through parchment, and was precipitable by acetone, alcohol, 

 ether, and colloidal iron. The substance was, of course, the now 

 well-known soluble specific substance which has so broadened our 

 conception of pneumococcal immunity. 



From a careful reading of Perlzweig's two papers (1921) 1078 " 9 

 there seems to be no doubt that he was dealing with the same sub- 

 stance but in impure state. From solutions of Pneumococcus in 

 bile-salts, by Rowland's anhydrous sodium sulfate method, and by 

 alcohol, Perlzweig precipitated an antigenic substance which he 

 considered was a nucleoprotein. However, on autolyzing the whole 

 organism or digesting it with proteolytic enzymes, the antigen was 

 found to be unimpaired. It was not injured by boiling for five min- 

 utes in neutral or slightly acid solution, but was destroyed by boil- 

 ing in alkaline solution. The substance could be recovered from 

 autolysates or digestion mixtures by extraction with alcohol in a 

 concentration of 70 to 85 per cent, but it was not soluble in 95 to 

 99 per cent alcohol. Perlzweig, 1079 and Perlzweig and Steffen, 1081 

 described the antigen as being soluble in neutral, acid, and alka- 

 line aqueous solutions but not in lipid solvents and, when tested 

 antigenically on white mice, it apparently possessed the complete 

 immunizing properties of the original pneumococcus. Because of 



* The finding recalls the observation of Preisziios (see Chapter II) who dem- 

 onstrated the presence of this substance in the blood of pneumonia patients, but 

 who thought it was mucin. 



