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 sugar, and this reserve stuff is distributed throughout the stalk after having been digested, exactly as would have been the case in the digestive canal of man.

Vegetables, then, really digest. The four classes of substances mentioned above are really digested in order to pass from their actual form, a form unsuitable for interstitial exchanges, to another form suitable for nutrition. As there are four kinds of foods, so there are four kinds of digestions, four kinds of ferment-producing agents—amylolytic, proteolytic, saccharine, and lipasic diastases, identical in the animal and the plant. Identity of ferments implies identity of digestions. Going down to the very basis of things, the digestive act is nothing but the action of this ferment. This is the crux of the whole question. All else is only difference in scene, varying in the means of execution and in the accessories. The difference arises from the stage on which it takes place, but the piece which is being played is the same, and the actors are the same, and so is the action of the play.

This identity between animal and vegetable life is found in the phenomena of respiration and of motility. The limits of this book do not allow of our entering into the details of facts. Besides, the facts are well known, and may be found in any treatise on general physiology. This science, therefore, enables us to perceive the imposing unity of life in its essential manifestations.