378 



NATHAN HERMAN AND LEO F. RETTGER 



extract and sodimn chloride. The amounts of the different 

 substances in solution are stated in the following tables. 



Another method of at least partial purification of proteose 

 consisted in dialyzing a concentrated solution of ''peptone." 

 It was to be expected that the simpler biuret-giving substances 

 which in their aggregate constitute what may be called the pep- 

 tone fraction of the commercial ''peptone" would pass through 

 the parchment membrane, leaving the more complex ingredients, 

 the proteose portion in particular, behind. The process of 

 dialysis was allowed to continue for from six to eight days. In 

 order to prevent bacterial decomposition of the dialysate it 



TABLE 9 

 Showing the utilization of "purified" proteose 



ORGANISMS 



Control 



B. subtilis and B. ramosus 



B. prodigiosus 



P. vulgaris, 2 strains 



P. mirabilis 



Staph, aureus and alhus, 4 strains. 



B. cloacae 



B. typhi and B. paratyphi A 



B. coli, 2 strains 



B. coll, 1 strain 



REACTION 



6.0 

 5.0 

 10.0 

 14.0 

 16.0 

 11.0 

 2.0 

 19.0 

 12.0 

 20.0 



SORENSEN 

 TEST 



10.0 

 78.0 

 68.0 

 10.0 

 12.0 

 11.0 

 22.0 

 11.0 

 12.0 

 10.0 



BIURET TEST 



1.0 



0.0 



0.0 



0.9 



1.0 



0.95 



0.95 



1.0 



1.0 



0.95 



Medium : 0.8 per cent proteose, 0.25 per cent beef extract, 0.5 per cent NaCl. 

 Incubation at 30°C. for three weeks. 



was boiled for a short period each day, and the water in the jar 

 was frequently changed. 



The experiments with the proteose media were conducted in 

 the same manner as those in which the commercial peptones 

 were employed. The results of the first series of tests are 

 recorded in table 9. The beef extract was added to encourage 

 bacterial development. Only those culture flasks which gave 

 positive evidence of growth were used. 



B. subtilis, B. ramosus and B. prodigiosus completely destroyed 

 the proteose, as shown by the biuret test. Proteus vulgaris and 

 P. mirabilis produced only a slight change, owing to their slow 



