160 BIOLOGY OF PNEUMOCOCCUS 



young bacterial cells. Trials with the solutions, with the superna- 

 tant fluid from an S vaccine, the filtrate from an S vaccine, puri- 

 fied soluble specific substance, and the filtrates of actively growing 

 S cultures, all gave negative results. 



ISOLATION OF THE TRANSFORMATIVE PRINCIPLE 



Alloway (1932) 8 evidently was more successful than his prede- 

 cessors in obtaining the transformative principle from the pneumo- 

 coccal cell. With filtered extracts of virulent S strains of Types I 

 and III he converted a Type IIR strain into S organisms of the 

 same specific type as that of the cells extracted. The author stated 

 that the constituents of the extract supplied an activating stimu- 

 lus of a specific nature in that the R pneumococci acquired the ca- 

 pacity of elaborating the capsular material peculiar to the organ- 

 isms extracted. 



In the next study (1933), Alloway 9 prepared active and spe- 

 cific extracts by dissolving S pneumococci in sodium desoxycholate 

 solution. These cell-free extracts were as potent as the intact cocci 

 in causing R forms to assume new type-specific characters. With 

 an extract of Type III Pneumococcus he was able to convert a 

 Type IIR variant almost regularly and abruptly into the smooth 

 form of Type III. Alloway then purified the extracts by removing 

 a considerable amount of inert material by charcoal adsorption 

 and reprecipitation of the adsorbed extracts with alcohol or ace- 

 tone. The stimulating principle passed through Berkefeld filters 

 without loss of strength if the reaction of the solution was alka- 

 line. The substance was resistant to heating at 60° for thirty min- 

 utes but was appreciably affected at temperatures of 80° or over. 

 The purified extracts apparently had suffered no loss of potency 

 and caused a more prompt transformation than did the original 

 solutions. An unexplained observation was the fact that in no in- 

 stance could the transformation be effected without the addition to 

 the culture-extract mixture of blood serum or of ascitic or pleural 

 fluid. 



