128 Edwin O. Jordan 



subtil is) cultures incubated at 37 . 5° gave more abundant production of 

 gelatinase in broth than in gelatin, while cultures kept at 20° showed 

 just the reverse. B. subtilis cultures in broth at 37.5° developed the 

 enzyme earlier than those at 20°, while B. proteus cultures gave a 

 larger amount of enzyme at 20° than at 37 . 5°. It is plainly incorrect 

 to compare the enzyme content of the liquefied gelatin produced at 

 room temperature with that of a whole flask of gelatin incubated at 

 37°. On the same ground, a comparison of broth and gelatin cultures 

 at 20° is open to objection. Sometimes old gelatin cultures are con- 

 siderably more potent than the corresponding broth cultures, but this 

 is not invariably true. (Table I, B. pyocyaneus, 59 days ; B. prodigiosiis, 

 39 days.) This seems in some cases to be due to the loss of the origi- 

 nal strength of the broth culture (cf. B. amyloruber). Whether the 

 difference depends upon an unequal rate of disappearance of the 

 enzyme in the two media or whether gelatinase production continues 

 in some cases in the gelatin culture after ceasing in the broth is uncer- 

 tain. 



The failure of the presence of gelatin to provoke the formation of 

 gelatinase does not seem to be peculiar to bacterial cultures. Mal- 

 fitano,' in working with Aspergillus niger, found that the kind of 

 enzyme produced by this mold did not depend upon the presence of 

 gelatin or upon the nature of the medium, except in so far as this influ- 

 enced the general development of the mycehum. And Butkewitsch' 

 states that although peptone hinders the action of the gelatinase 

 formed by Aspergillus and Penicillium, this enzyme is produced 

 abundantly in a medium containing peptone. 



Particular interest attaches to the question of gelatinase production 

 in non-proteid media., Fermi^ averred that most bacteria formed no 

 enzymes upon proteid-free media, only B. pyocyaneus and B. prodi- 

 giosus — among those tested by him — giving positive results. Fermi 

 does not specify the media employed further than to state that his 

 experiments were made "auf Phosphor- Ammonium-Nahrsalzen mit 

 Zusatz von Zuckcr oder Glycerin." The microbes mentioned above 

 were said to produce their enzymes only in the media containing 

 glycerin, not in those with sugar. Katz,"* on the other hand, was 

 unable to confirm Fermi's observation that B. megatherium did not 



■ Ann. de I' Inst. Past., 1890, 14, p. 60. ^ Centralbl. /. Bakt., 1891, 10, p. 405. 



' Jahrb, wiss. Bot., 1903, 38, p. 147. * Jahrb. wiss. Bot., 1898, 31, p. 599- 



