14 Mendel and Underhill — Papdin-digestion. 



Similarly the enzyme found by Green' in the germinating seeds of 

 Lupinus hirsutvs acts in acid media, forming leucin and tyrosin ; 

 but the primary products are also found. Related enzymes have 

 been described by others. The proteolytic enzyme of the pitcher 

 plant, Nepenthes, which Vines'^ has studied, seems to resemble pepsin 

 most closely ; for it acts only in acid fluids, forming large quantities 

 of albumoses, small amounts of peptone and only traces of leucin, if 

 any. Tyrosin has not been obtained. In writing of various vege- 

 table enzymes. Vines says : " It is a remarkable fact that, whatever 

 may be the reaction of the medium in which they can work, all these 

 enzymes are essentially tryptic in their mode of action ; in fact it is 

 not improbable that this may be a. characteristic feature of all vege- 

 table proteolytic enzymes whatsoever.'" On the contraiy, we 

 believe that the actual experiments of Vines, as well as the work 

 recorded in this paper, make it more probable that plants, like 

 animals, produce various kinds of proteolytic enzymes.* 



April, 1901. 



• Green : Philosophical Transactions of the Royal Society, London, 1887, B, 

 clxxviii, p. 39. 



•^ Vines : Annals of Botany, 189?, xi, p. 563 ; 1898, xii, p. 546. 



^ Vines: loc. cit., 1898, xii, p. 555. 



^ Gf. Pfeffer : Pflauzenphysiologie, 1897, i, p. 511-512. 



