La Digestion Végétale, Note sur le Rôle des Ferments dans la Nutrition des Plantes

Abstract

THIS paper is brought forward by Prof. Morren as a supplement to his observations on carnivorous plants. Its main point is the statement that digestion is not a function exclusively of those plants termed “carnivorous” but is a process common to all living beings, vegetable as well as animal. Animal digestion is, he states, according to the most approved view, a process of fermentation consisting essentially in a transformation of colloids into crystalloids, this change being a necessary preliminary to absorption. In the same manner all plants digest; and the process is precisely analogous to that of animals, and is again essential before assimilation is possible. The ordinary vegetable ferment for the conversion of starch into glucose is diastase, which has been detected in barley; it occurs also in the tubers of the potato, near the “eyes.” For the fermentation or digestion of nitrogenous substances, albuminoids, a different ferment is required, and this we have in pepsine, which has been detected by several observers in the viscid secretion of Nepenthes, Drosera, and other insectivorous plants. According to Masters, it occurs also in the nectaries of Helleborus; and a similar substance has long been known in the latex of Carica Papaya. Vegetable digestion is therefore as widely diffused and as various a phenomenon as animal digestion, and consists in the transformation of the raw insoluble food material into soluble crystalloids capable of assimilation. It takes place chiefly in the “reservoirs of reserve-material”—seeds, underground stems, roots, the bark, the pith. The nutrition of plants is made up of three successive processes:—elaboration, digestion, assimilation. The first consists in the production, out of its elements, of a carbo-hydrate, and can take place only under the influence of light. Digestion consists essentially in hydration—as in the conversion of starch into glucose—and is associated with an evolution of carbonic acid. It is accompanied by a molecular change which renders the resulting product soluble and diffusible. Assimilation is simply the absorption by the living tissue of the substances thus prepared, one of the chief processes which accompanies it being the reversion, by loss of water, of the glucose to the condition of cellulose, a substance isomeric but not isomorphic with starch. Intussusception, therefore, is a process which can only succeed digestion. No essential difference can, in fact, be maintained between the manner in which animals and plants digest their food.

La Digestion Végétale, Note sur le Rôle des Ferments dans la Nutrition des Plantes.

E.

Morren

Par. (Gand, 1876.)