380 



NATHAN BERMAN AND LEO F. RETTGER 



the ease with which the organism produces its proteolytic enzyme 

 and by the unusual activity of this enzyme when present in 

 very small amount. None of the other bacteria employed was 

 able to increase in numbers in the proteose medium, all of the 

 flasks remaining as clear as the control. 



A series of tests was carried out also with the diphtheria bacil- 

 lus, and the results recorded in table 11. Both strains of the 

 organism used were unable to produce any change in the pro- 

 teose content, as is shown clearly by the biuret tests, and corrob- 

 orated by the Sorensen figures. Multiplication of the organ- 

 isms was entirely at the expense of the meat extract. Whether 

 any of the albumoses are affected by B. diphtheriae without 

 losing their biuret-giving property remains undetermined. This 



Medium: 0.5 per cent proteose, 0.5 per cent beef extract, 0.5 per cent NaCl 

 Incubation at 30°C. for three weeks. 



question is of particular interest in view of Hida's (1908) claim 

 that deutero-albumose is essential in diphtheria toxin production. 



THE UTILIZATION OF GELATIN AND CASEIN 



Although a large number of organisms are known to liquefy 

 gelatin, little has been done to determine whether the gelatin is 

 actually utilized by the bacteria. Experimental evidence was 

 sought in this work as to whether the power to liquefy gelatin 

 carries with it ability to reduce it to its simple components. 

 It has already been pointed out that the gelatinolytic and albu- 

 molytic properties of an organism may be distinct. The test 

 medium employed in this investigation contained gelatin as the 

 only known source of organic nitrogen. 



