442 SCIENCE PROGRESS 



enzyme having a wide range of action, limited in one direction 

 by o - 5 per cent, of hydrochloric acid, and in the other by a 

 greater amount than i"5 per cent, of sodic carbonate, and a 

 peptone-splitting enzyme of narrower range, not extending 

 beyond i"5 per cent, of the alkali. 



With bromelin, peptolysis but not fibrin-digestion was com- 

 pletely inhibited by alkalinity. 



With yeast the results were not quite the same — the range 

 for peptolysis was greater than that for digestion of fibrin ; in 

 the former case proteoclastic activity was shown to extend from 

 about 3 per cent, of sodic carbonate to 0*5 percent, of hydrochloric 

 acid, in the latter from about 1 per cent, of the alkali, to 01 per cent, 

 of the acid. Yeast thus gives results which are the converse 

 of those yielded by the papaw and the pineapple. Slightly 

 different effects were observed in the case of the mushroom ; 

 peptolysis was retarded by acid but promoted by alkali, while 

 fibrin digestion was arrested by deviation from the normal 

 reaction, whether acid or alkaline. 



Vines confirmed the observations of Weis as to the existence 

 of two proteases in malt, or germinating barley, using, however, 

 proteids of animal origin in his experiments, while Weis 

 employed chiefly glutin and legumin. He found further that 

 the pepsin is more readily affected than the erepsin by dilute 

 alkalis ; the inhibition of the former was complete in the 

 presence of 1 per cent, sodic carbonate, but the erepsin acted, 

 though slowly, for twenty-four hours. 



The extract of the hyacinth bulb can digest both fibrin and 

 peptone in an alkaline medium, though the natural reaction of 

 the juice is faintly acid. Fibrin digestion is more readily 

 affected than peptolysis by increased acidity or alkalinity. 



Experiments on nepenthin showed that the liquid in the 

 pitcher of Nepenthes peptonises fibrin much more rapidly than 

 it decomposes Witte-peptone ; fibrin-digestion is inhibited by 

 alkalinity, but promoted by acidity ; peptone-decomposition, 

 which is slow in any case, is much retarded by alkalinity, but 

 is not inhibited by the small percentage (0*15 per cent, of sodic 

 carbonate) that arrested the digestion of fibrin. 



Summarising his results, Vines states that peptolysis takes 

 place within a range extending from distinct alkalinity to a 

 degree of acidity beyond the natural reaction of the plant from 

 which the particular enzyme is extracted ; fibrin-digestion is 



