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 ''The Doctrine of the Vital Duality of Animals and Plants.''—There are, therefore, biologists who, in the domain of theory and in virtue of more or less well-founded conceptions or interpretations, separate elementary life from other vital forms, and thus break the bond of vital unity proclaimed by Claude Bernard. This monistic doctrine at the outset met with other opponents, and that, too, in the domain of facts. But it triumphed over them and became established. We have to deal with scientists like J. B. Dumas and Boussingault, who drew a dividing line between animal life and vegetable life.

But let us in a few words recall to the reader this victorious struggle of the monistic doctrine against the dualism of the two kingdoms. If we consider an animal in action, said the champions of vital dualism, we agree that it feels, moves, breathes, digests, and finally, that it destroys by a real operation of chemical analysis the materials afforded to it by its ambient world. It is in these phenomena that are manifested its activity, its life. Now, added the dualists, plants do not feel, do not move, do not breathe, and do not digest. They build up from immediate principles, by an operation of chemical synthesis, the materials they borrow from the soil which bears them, or from the atmosphere which surrounds them. There is, therefore, nothing in common between the representatives of the two kingdoms if we confine ourselves to the examination of the actual phenomena which take place in them. To find a resemblance between the animal and the vegetable, said the dualists, we must set aside what they do, for they do different, or even contrary things. We must consider whence they come and what they become. Both originate