310 BIOLOGY OF PNEUMOCOCCUS 



decomposed, and filtered autolysates of the cell suspension exhib- 

 ited tremendously enhanced enzymatic activity. For a given 

 amount of capsular polysaccharide decomposed in the new phos- 

 phate-yeast medium, the yield of enzyme obtained was much larger 

 than that recovered by the former cultural methods. The produc- 

 tion of the enzyme always failed when conditions in the substrate 

 were unfavorable to cellular multiplication. 



With Bauer, Dubos 338 then described an improved technique for 

 concentrating and purifying the enzyme preparations. They fil- 

 tered the solution, made in the manner just described, under fifty 

 pounds pressure through collodion membranes of the type de- 

 scribed by Bauer and Hughes. 90 The enzyme, under optimal condi- 

 tions of filtration, passed through membranes of an average pore 

 size of 10.6 mpi but was held back by pores having a diameter of 

 8.2 mu. When the enzyme solutions were filtered to dryness through 

 membranes of such porosity as to hold back the active principle, 

 and when proper precautions were taken to prevent or minimize 

 adsorption, such as the preliminary "greasing" of the collodion 

 membrane with meat-infusion peptone broth, the enzyme could be 

 completely recovered by immersing the membrane in distilled water 

 or physiological salt solution. 



EFFECT OF ENZYME ON INFECTION INDUCED IN RABBITS 



In 1932, Goodner, Dubos, and Avery 536 studied the action of the 

 enzyme on the dermal infection of rabbits induced with Type III 

 Pneumococcus, employing the Type III strain virulent for rabbits 

 previously described by Tillett. The culture was grown in rabbit- 

 blood broth and its virulence was maintained for rabbits by fre- 

 quent animal passage. Of the blood-broth culture 10" 8 cubic centi- 

 meters given intraperitoneally sufficed to kill mice within ninety-six 

 hours, and when given intradermally into rabbits 0.000,01 cubic 

 centimeter caused death or a protracted disease of severe charac- 

 ter. The enzyme preparations were, for the larger part, purified 

 and concentrated by the method of Dubos. The intradermal infec- 



