LIXXEAJf SOCIETX OF LONDOX. 43 



Bidbs : Onion; Tulip; Hyacintli. 



Tubers : Jerusalem Artichoke ; Potato. 



Leaves : Cabbage ; Tropa'oJum majus ; Dalilia variabilis ; Mira- 

 bilis Jalapa ; Spiiiacia oleracea ; Holcus mollis ; PJialaris 

 canaricnsis : Pnums Lauro-cerasus ; Hdianthas tuberosus ; 

 Hicinus cominunis ; Ajiium graveolens (both green and 

 etiolated); Pelargonium zonule; the Fern Scolopendrixon 

 vulgar e, but here digestion was slow. 



Roots : Turnip ; Tomato ; Vegetable Marrow ; Phaseolus rnulti- 

 florus ; Alirabilis Jalapa ; Daucus Garota. 



Fungi : the Mushroom. 



Having established the presence of a proteolytic enzyme, the 

 next step was to ascertain whether the tissues or juices of the 

 plants under investigation were capable (like the Pineapple, 

 the Fig, the Papaw, etc.) of peptonising the higher proteids. 

 Evidence of the peptonisation of fibriu and of the caseiuogeu of 

 milk was obtained in the case of the juice of the Melon, of the 

 watery extract of the Lettuce, and of the tissue of the Mushroom. 

 The results in other cases were either doubtful or negative. There 

 was frequently evidence that the proteids naturally existing in the 

 vegetable substances themselves had been digested. 



The experiments definitely establish the fact that an enzyme 

 which actively proteolyses the simpler forms of proteid is present 

 in all parts of the plant-body. But the question as to the precise 

 nature of this enzyme still remains to be answered. Where pro- 

 teoh'sis is accompanied by peptonisation, it may be inferred that 

 the enzyme is allied to the trypsin of the animal body. "Where 

 no peptonisation, but only proteolysis, can be detected, it seems 

 probable that the enzyme is allied to the erepsin recently discovered 

 by Cohnheim in the small intestine. Possibly more than one 

 enzyme rnaj' be active in certain cases. 



The conclusions arrived at depend entirely upon the reliability 

 of the tryptophane-reaction as evidence of proteolysis. From 

 what is known as to its chemical composition and as to the con- 

 ditions of its formation in digestion, there can be no doubt that 

 tryptophane is a product of the disruption of the proteid molecule. 

 The point that had more particularly to be determined was whether 

 the substauce giving the colour-reaction with chlorine in these 

 experiments is really tryptophane. The isolation of tryptophane 

 is a difficult process, and was not attempted. Tlie chemical 

 identity of the substance is, however, established by the fact that 

 its chlorine-compound was found to give the same absorption- 

 spectrum as does that of tryptophane, namely, a band in the 

 green on the yellow side of the thallium-liue. 



Mr. A. G. Taxsley, F.L.S., in his paper, illustrated by lantern- 

 slides, '' The Eelation of Histogenesis to Tissue-Morphology," 

 dealt with a few points bearing on the relation of histogenesis at 

 the apex of the stem in the Pteridophyta to the morphology of 

 the tissue-regions in the adult stem. 



