_Summa summarum_: The evolutionary argument from homology is defective in three important respects: (1) in its lack of experimental confirmation; (2) in its incomplete enumeration of the disjunctive possibilities; (3) in its inability to construct a scheme of transmutation that synthesizes inheritance and variation in a logically coherent, and factually substantiated formula. The first two defects are not necessarily fatal to the argument as such. Though they destroy its pretensions to conclusiveness, they do not preclude the fulfilment of the moderate claim made in its behalf by Prof. T. H. Morgan, who says: “In this sense (_i.e._, as previously stated) the argument from comparative anatomy, while not a demonstration, carries with it, I think, a high degree of probability.” (“A Critique of the Theory of Evolution,” p. 14.) The third defect is more serious. The apparently irreducible antagonism which the evolutionary assumption introduces between inheritance and variation has been sensed even by the adherents of transformism themselves, and they have searched in vain for a formula, which, without sacrificing the facts, would bring into concord the respective rôles of these discordant factors. “It follows,” says Osborn, “as an unprejudiced conclusion from our present evidence that upon Weismann’s principle we can explain inheritance but not evolution, while with Lamarck’s principle and Darwin’s selection principle we can explain evolution, but not, at present, inheritance. Disprove Lamarck’s principle and we must assume that there is some third factor in evolution of which we are ignorant.” (_Popular Science Monthly_, Jan., 1905.) The point is well taken, and unless, as Osborn suggests, there is a _tertium quid_ by means of which the discord can be resolved into ultimate harmony, we see no way of liberating the theory of Transmutation from this embarrassing dilemma. CHAPTER III FOSSIL PEDIGREES “_By dint of such great efforts we succeeded only in piecing together genial romances more or less historical._”—B. Grassi, Prof. of Comparative Anatomy, Univ. of Rome, “La vita” (1906), p. 227. § 1. =The Argument in the Abstract=