But we may conclude, from the facts presented above, that if there is such a naturally delimited group as a "species" in the Linnæan sense of the word, it by no means coincides with what now passes under this name, but might include many so-called species, often a whole genus, or even several. With this in mind, we must pass on to consider the next step in our study, as to whether new "species" are now coming into being in our modern world under scientific observation, either natural or artificial. VI MENDELISM AND THE ORIGIN OF SPECIES "Had Mendel's work come into the hands of Darwin, it is not too much to say that the history of the development of evolutionary philosophy would have been very different from that which we have witnessed."[23] [Footnote 23: William Bateson, "Mendel's Principles of Heredity," p. 316.] I From the latter part of the eighteenth century, attempts were continually being made to explain the origin of all organic forms by some system of development or evolution. Buffon had dwelt on the modifications directly induced by the environment. Lamarck had made much use of this idea, claiming that such modifications were transmitted to posterity, and claiming the same for the structural changes produced by use and disuse. Lamarck's work did not become at all popular while he lived, chiefly through the overpowering influence of Baron Cuvier, who had an equally fantastic scheme of his own, which may well be termed a burlesque on Creation and in which an extreme fixity of "species" was a cardinal doctrine. Erasmus Darwin and Robert Chambers in England also tried to make a theory of evolution believable; though their efforts were but little more successful in gaining the ear of the world. But to all that had gone before Charles Darwin and A.R. Wallace (1858) added the idea of "natural selection," or "the struggle for existence," to use the respective terms coined by each of these authors, as the chief means by which the effects of variation are accumulated and perpetuated so as to build up the modern complexities of the plant and animal kingdoms. Partly because it was a psychological moment, from the fact that the uniformitarian geology of Lyell with its graded advance of existences from age to age seemed absolutely to demand some evolutionary explanation; partly because artificial selection was a familiar idea of proved value in selective breeding, and "natural selection" seemed an exact parallel carried on by nature in the direction of continual improvement; but perhaps more largely because the abstract idea of "natural selection" involved so many intricate separate concepts that for nearly a generation scarcely two naturalists in the world could state the whole problem of the theory exactly alike;--on all these accounts the theory of natural selection, or of the "survival of the fittest," to use the phrase of Herbert Spencer, became in the latter decades of the nineteenth century well-nigh universal.