Proceedings of the Linnean Society of London - University Library

LINNEAX SOCIETY OF LONDON. 1
the remarkable facts recently brought to light with regard to
proteid-digestion in animals.
Let me, to begin with, very briefly trace the history of
discovery concerning the digestion of proteids by plants. The
first definite evidence of its occurrence was obtained as the i*esult
of the investigation of insectivorous plants by Mr. Darwin,
Sir Joseph Hooker, and Prof. Lawson Tait : in fact, the publication
of Mr. Darwin's book on ' Insectivorous Plants," in 1875,
may be taken as the starting-point. Almost simultaneously a
digestive ferment or enzyme was discovered by von Gorup-
Besanez in the germinating seeds of various plants. This was
followed, in 1879, by AVurtz's demonstration of the digestive
activity of the juice of the Papaw, which was confirmed and
extended by Dr. Martin a few years later. About this time,
Hansen investigated the digestive property of the latex of the
Fig-tree, which had been first observed by Bouchut in 1880.
Shortly afterwards the digestive processes in germinating seeds
were further investigated by Prof. Eeynolds Green. In 1891,
Professor Chittenden published his important researches into the
very remarkable digestive action of Pineapple-juice upon proteids ;
and in the following year, Prof. Green discovered that a similar
property was possessed by the juice of a species of Gourd
{Cucumis utiltssimits).
In 1896, I took up afresh the study of the digestive action
of the liquid of the well-known insectivorous pitcher-plant
Nepenthes, because the accuracy of the earlier observations on
the subject bad been called in question. It had been stated by
Prof. Dubois, amongst others, that the apparent digestive activity
in this case was due, not to any enzyme secreted by the plant
itself, but to the intervention of Bacteria. I made a number
of experiments under antiseptic conditions, with the pitcher-
liquid of Nepenthes, which seem to me to refute the theory of
Bacterial action and to uphold the conclusions of the original
observers. Having become once more interested in the subject,
I proceeded to investigate in greater detail the digestive processes
in Nepenthes and in other plants in which they were then known
to take place, the results of which I shall presently give some
account. But what is perhaps more important, I was led on to
examine many plants and parts of plants in which such processes
were not suspected, to see if any trace of them could be detected,
and I succeeded in doing so in almost every case. I have obtained
positive results with such fruits and parts of fruits as the
Melon, the Grape, Orange-peel, the Banana : with the foliageleaves
of the Dahlia, the Lettuce, the Cabbage, the Spinach, and
many others : with the bulbs of the Tulip and the Hyacinth : the
tubers of the Potato and the Jerusalem Artichoke : the tuberous
roots of the Beet, the Dahlia, and the Turnip ; as also with
Yeast, and with the Mushroom among Fungi. I may in fact
venture to assert that the presence of a protease, or
c2proteid-
9