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With animals, according to Schiff, mechanical irritation excites the glands of the stomach to secrete an acid, but not pepsin. There is strong reason to believe, too, that the glands of Drosera, which are continually secreting viscid fluid to replace the losses by evaporation, do not secrete the ferment proper for digestion when mechanically irritated, but only after absorbing certain matters of a nitrogeneous nature. The glands of the stomachs of animals secrete pepsin only after they have absorbed certain soluble substances designated peptogenes, showing a remarkable parallelism between the glands of Drosera and those of the stomach in the secretion of their appropriate acid and ferment.

Not only animal matter, but also the albumen of living seeds, which are injured or killed by the secretion, are acted upon by the glands of Drosera. Matter is likewise absorbed from pollen, and from fresh leaves. The stomachs of vegetable-feeding animals, as is only too well known, possess a similar power of extracting nourishment from such articles. Though properly an insectivorous plant, but as pollen, as well as the seeds and leaves of surrounding plants, cannot fail to be often or occasionally blown upon the glands of Drosera, yet it must be credited with being to a certain extent a vegetable feeder.