It will, of course, be interesting to realize what the bearing of Mendel's discoveries is on the question of the stability of species as well as on the origin of species. Professor Morgan, in his {216} article on Darwinism in the "Light of Modern Criticism," already quoted, says the important fact (with regard to Mendel's Law) from the point of view of the theory of evolution is that "the new species have sprung fully armed from the old ones, like Minerva from the head of Jove." "From de Vries's results," he adds, "we understand better how it is that we do not see new forms arising, because they appear, as it were, fully equipped over night. Old species are not slowly changed into new ones, but a shaking up of the old organization takes place and the egg brings forth a new species. It is like the turning of the kaleidoscope, a slight shift and the new figure suddenly appears. It needs no great penetration to see that this point of view is entirely different from the conception of the formation of new species by accumulating individual variations, until they are carried so far that the new form may be called a new species." With regard to this question of the transformation of one species into another, Mendel himself, in the concluding paragraphs of his article on hybridization, seems to agree with the expressions of Morgan. He quotes Gärtner's opinion with apparent approval: "Gärtner, by the results of these transformation experiments was led to oppose the opinion of those naturalists who dispute the stability of plant species and believe in a continuous evolution of vegetation. He perceives in the complete transformation of one species into another an indubitable proof that {217} species are fixed within limits beyond which they cannot change." "Although this opinion," adds Mendel, "cannot be unconditionally accepted, we find, on the other hand, in Gärtner's experiments a noteworthy confirmation of that supposition regarding the variability of cultivated plants which has already been expressed." This expression of opinion is not very definite, and Bateson, in what Professor Wilson of Columbia calls his "recent admirable little book on Mendel's principles," adds the following note that may prove of service in elucidating Mendel's meaning, as few men have entered so fully into the understanding of Mendel's work as Bateson, who introduced him to the English-speaking scientific public, "The argument of this paragraph appears to be that though the general mutability of natural species might be doubtful, yet among cultivated plants the transference of characters may be accomplished and may occur by _integral steps_ [italics ours], until one species is definitely 'transformed' into the other."