376 



NATHAN BERMAN AND LEO F. RETTGER 



this reason a very important ingredient of the ordinary labora- 

 tory media. The older belief in a mere "stimulating effect" of 

 meat extract on bacteria is unscientific and untenable. The 

 real food value lies in the amino acids (primary and secondary) 

 and in the so-called "extractives, kreatin, kreatinin, hypoxanthin, 

 etc." 



The behavior of St. aureus, St. albus and B. cloacae in the 

 peptone was surprising. These gelatin-liquefying organisms 

 were able to attack the biuret-positive substances to only a 



TABLE 6 

 Showing utilization of Armour's peptone 



ORGANISMS 



Control 



Subtilis groups, 3 members . 



B. prodigiosus 



P. vulgaris, 2 strains 



P. mirahilis 



Staph, aureus and albus, 4 strains... 



B. cloacae 



B. typhi, and B. paratyphi A and B. 



B. coli, 4 strains 



B. diphtheriae, 2 strains 



BEACTION 



20.0 



5.0 



4.0 



1.0 

 8.0 

 7.0 

 2.0 

 5.5 

 3.5 

 7.0 



SORENSEN 

 TEST 



30.0 

 60.0 

 54.0 

 56.0 

 66.0 

 60.0 

 53.0 

 50.0 

 52.0 

 54.0 



BIDRET TEST 



1.0 



0.0 



0.0 



0.0 



0.4 



0.5 



0.5 



0.65 



0.57 



0.5 



Medium: 0.5 per cent peptone, 0.25 per cent beef extract, 0.5 per cent NaCl. 

 Incubation at 30°C. for three week's. 



slightly greater extent than the non-liquefiers. This observation 

 is in accord, however, with those of Malfitano (1903) who 

 pointed out a distinct difference between the albumolytic and 

 the gelatinolytic properties of an organism. In his work with 

 B. anthracis he showed that the addition of chloroform influenced 

 the albumin-digesting, but not the gelatin liquefying property. 

 A further review of the literature (Mavrojannis, 1903, and 

 Jordan, 1906) justifies the conclusion that the ability of an 

 organism to liquefy gelatin is no indication of its proteolytic 

 power. 



