excitement changes in Nature and becomes acid.  So, according to Schiff, mechanical irritation excites the glands of the stomach to secrete an acid.  In both this acid appears to be necessary to, but of itself insufficient for, digestion.  The requisite solvent, a kind of ferment called pepsin, which acts only in the presence of the acid, is poured forth by the glands of the stomach only after they have absorbed certain soluble nutritive substances of the food; then this pepsin promptly dissolves muscle, fibrine, coagulated albumen, cartilage, and the like.  Similarly it appears that Drosera-glands, after irritation by particles of glass, did not act upon little cubes of albumen.  But when moistened with saliva, or replaced by bits of roast-meat or gelatine, or even cartilage, which supply some soluble peptone-matter to initiate the process, these substances are promptly acted upon, and dissolved or digested; whence it is inferred that the analogy with the stomach holds good throughout, and that a ferment similar to pepsin is poured out under the stimulus of some soluble animal matter.  But the direct evidence of this is furnished only by the related carnivorous plant, Dionaea, from which the secretions, poured out when digestion is about to begin, may be collected in quantity sufficient for chemical examination.  In short, the experiments show “that there is a remarkable accordance in the power of digestion between the gastric juice of animals, with its pepsin and hydrochloric acid, and the secretion of Drosera, with its ferment and acid belonging to the acetic series.  We can, therefore, hardly doubt that the ferment in both cases is closely similar, if not identically the same.  That a plant and an animal should pour forth the same, or nearly the same, complex secretion, adapted for the same purpose of digestion, is a new and wonderful fact in physiology.”

There are one or two other species of sundew—­one of them almost as common in Europe and North America as the ordinary round-leaved species—­which act in the same way, except that, having their leaves longer in proportion to their breadth, their sides never curl inward, but they are much disposed to aid the action of their tentacles by incurving the tip of the leaf, as if to grasp the morsel.  There are many others, with variously less efficient and less advantageously arranged insectivorous apparatus, which, in the language of the new science, may be either on the way to acquire something better, or of losing what they may have had, while now adapting themselves to a proper vegetable life.  There is one member of the family (Drosophyllum Lusitanicum), an almost shrubby plant, which grows on dry and sunny hills in Portugal and Morocco—­which the villagers call “the flycatcher,” and hang up in their cottages for the purpose—­the glandular tentacles of which have wholly lost their powers of movement, if they ever had any, but which still secrete, digest, and absorb, being roused to great activity by the contact of any animal matter.  A friend of ours once remarked that it was fearful to contemplate the amount of soul that could be called forth in a dog by the sight of a piece of meat.  Equally wonderful is the avidity for animal food manifested by these vegetable tentacles, that can “only stand and wait” for it.