Proceedings of the Linnean Society of London - University Library

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 proteoh'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 conditions
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 absorptionspectrum
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 lanternslides,
'' 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.