areolar tissue, or the fibrous basis of bone. It is not known how long an animal would survive if fed on fibrin alone, but Dr. Sanderson has no doubt longer than on gelatine, and it would be hardly rash to predict, judging from the effects on Drosera, that albumen would be found more nutritious than fibrin. Globulin likewise belongs to the Proteids, forming another sub-group, and this substance, though containing some matter which excited Drosera rather strongly, was hardly attacked by the secretion, and was very little or very slowly attacked by gastric juice. How far globulin would be nutritious to animals is not known. We thus see how differently the above specified several digestible substances act on Drosera; and we may infer, as highly probable, that they would in like manner be nutritious in very different degrees both to Drosera and to animals. The glands of Drosera absorb matter from living seeds, which are injured or killed by the secretion. They likewise absorb matter from pollen, and from fresh leaves; and this is notoriously the case with the stomachs of vegetable-feeding animals. Drosera is properly an insectivorous plant; but as pollen cannot fail to be often blown on to the glands, as will occasionally the seeds and leaves of surrounding plants, Drosera is, to a certain extent, a vegetable-feeder. Finally, the experiments recorded in this chapter show us 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, [page 135] 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. But I shall have to recur to this subject in the fifteenth chapter, in my concluding remarks on the Droseraceae. [page 136] CHAPTER VII. THE EFFECTS OF SALTS OF AMMONIA. Manner of performing the experiments—Action of distilled water in comparison with the solutions—Carbonate of ammonia, absorbed by the roots—The vapour absorbed by the glands—Drops on the disc—Minute drops applied to separate glands—Leaves immersed in weak solutions—Minuteness of the doses which induce aggregation of the protoplasm—Nitrate of ammonia, analogous experiments with—Phosphate of ammonia, analogous experiments with—Other salts of ammonia—Summary and concluding remarks on the action of salts of ammonia.