as protoplasm, chlorophyll, gluten, aleurone, and of carrying them from one part to other parts of their tissues.  This must be effected by a solvent, probably consisting of a ferment together with an acid.  Now, in the case of plants which are able to absorb already soluble matter from captured insects, though not capable of true digestion, the solvent just referred to, which must be occasionally present in the glands, would be apt to exude from the glands together with the viscid secretion, inasmuch as endosmose is accompanied by exosmose.  If such exudation did ever occur, the solvent would act on the animal matter contained within the captured insects, and this would be an act of true digestion.  As it cannot be doubted that this process would be of high service to plants

* ‘Trait de Botanique’ 3rd edit. 1874, p. 844.  See also for following facts pp. 64, 76, 828, 831.

  Since this sentence was written, I have received a paper by
  Gorup-Besanez (’Berichte der Deutschen Chem.  Gesellschaft,’ Berlin,
1874, p. 1478), who, with the aid of Dr. H. Will, has actually made the discovery that the seeds of the vetch contain a ferment, which, when extracted by glycerine, dissolves albuminous substances, such as fibrin, and converts them into true peptones. [page 363]

growing in very poor soil, it would tend to be perfected through natural selection.  Therefore, any ordinary plant having viscid glands, which occasionally caught insects, might thus be converted under favourable circumstances into a species capable of true digestion.  It ceases, therefore, to be any great mystery how several genera of plants, in no way closely related together, have independently acquired this same power.

As there exist several plants the glands of which cannot, as far as is known, digest animal matter, yet can absorb salts of ammonia and animal fluids, it is probable that this latter power forms the first stage towards that of digestion.  It might, however, happen, under certain conditions, that a plant, after having acquired the power of digestion, should degenerate into one capable only of absorbing animal matter in solution, or in a state of decay, or the final products of decay, namely the salts of ammonia.  It would appear that this has actually occurred to a partial extent with the leaves of Aldrovanda; the outer parts of which possess absorbent organs, but no glands fitted for the secretion of any digestive fluid, these being confined to the inner parts.

Little light can be thrown on the gradual acquirement of the third remarkable character possessed by the more highly developed genera of the Droseraceae, namely the power of movement when excited.  It should, however, be borne in mind that leaves and their homologues, as well as flower-peduncles, have gained this power, in innumerable instances, independently of inheritance from any common parent form; for instance, in tendril-bearers and leaf-climbers (i.e. plants with their leaves,