in the way of the adoption of a general theory of development, which the labors of many men in different fields had been preparing. The ship was on the stays, prepared to glide into the ocean, when Darwin came and knocked away one or two of the blocks that had been most obstinately hindering her descent. The wonderful success of the Darwinian theory was chiefly due to this very circumstance, that so much had been already done to facilitate its acceptance. The doctrine of the correlation of force, to which Dr. Porter assigns the fourth place, was, if we date it only from the publication of Grove's treatise, seventeen years old when the "Origin of Species" appeared. The nebular hypothesis had been waiting for over a hundred years, or since the publication of Kant's "General History of Nature and Theory of the Heavens." The progress of society and perfectibility of human nature were the commonplaces of the last century, which was also thoroughly familiar with the discussion as to spontaneous generation, or the development of the organic from the inorganic. Why the arguments from biology should be separated from Darwinism proper it is difficult to see, considering that Darwin, from the first, based his theory of the origin of species on biological grounds, quite as distinctly as on the operation of the struggle for existence. It is Darwin, above all men, who has popularized the arguments from rudimentary organs and from the changing phases of embryonic life. Could Dr. Porter have made good his promise to describe to us the evolution of evolution, if we may so express it, he would have done a very useful work; but the fact is, he has not even attempted it, but has simply given us what, if we may be allowed for once to adopt a common misquotation of Horace, may very truly be called the disjecta membra of a philosophy.
Leaving this point, however, let us inquire what the author of the "Lecture on Evolution" has to say on the several heads into which he has divided the subject. In regard to "Darwinism," he finds the evidence for the transformation of species insufficient. He admits the tendency to variation and the struggle for existence; but does not see that these, alone or principally, determine the origin of species. One may go a long way with Darwin, he says, and yet fail to draw the conclusion that three or four original types have been the ancestors of all other organic forms past and present. This language is dubious. It might suggest that, had Darwin been a little more liberal with his archetypes, the learned doctor would have agreed with him fully. What is it "to go a long way with Darwin"? The mere recognition of the tendency to variation and the struggle for existence is not to go with Darwin at all: it is merely to accept his starting-point, and to recognize facts that were fully recognized long before his time. It is a pity that so doughty a champion of orthodoxy as Dr. Porter does not tell us more distinctly what his own position is. Apparently be rejects the theory of transformation by change of environ-
