138 



Edwin O. Jordan 



EXPERIMENT. 



These experiments show that not all gelatin-liquefying enzymes 

 area like in respect to the conditions of their activity ; that some liquefy 

 a neutral gelatin quite as rapidly as, or even better than, a slightly 

 alkaline one (B. amyloruber, B. prodigiosus); that some liquefy even 

 more rapidly in an acid medium than in an alkaline one (B. pyocya- 

 neus); and that in one case alkaline carbol gelatin is Hquefied more 

 rapidly than a neutral gelatin {Sp. Finkler-Prior). Vines' has 

 recently shown that the digestion of fibrin by vegetable proteases 

 occurs in some cases with both acid and alkaline reaction and in 

 others is limited to acid reaction. He interprets his results as indi- 

 cating the existence of two distinct vegetable proteases, one of which 

 belongs to the peptases, although the "vegetable pepsin" differs 

 from animal pepsin in being able in some cases to act in an alkaline 

 medium. 



I have already pointed out that the acid reaction developed in the 

 course of gelatin digestion interferes with any strict evaluation of 

 the influence of reaction upon the work of the gelatinases. For 

 example, tubes of carbol gelatin with an initial reaction 2 per cent 

 alkaline were liquefied in 20 hours by the enzymes of B. prodigiosus 

 and Sp. Finkler-Prior respectively, and both tubes then had a reaction 

 of but 0.4 per cent alkaline. By the action of trypsin for 20 hours 



' Annals of Botany, 1905, 19, pp. 149-87. 



