Weismann’s work on the germ-plasm in pursuance of a theory of heredity is pronounced by Romanes to have remained up to 1893 substantially unaltered, though largely added to in matters of detail, and at the present time as far as I gather from a study of the more recent literature this theory holds the field or at least a commanding position in it.[26] Originally he held that the germ-plasm possessed _perpetual_ continuity since the first origin of life, and _absolute_ stability since the first origin of sexual propagation, but he has shown himself willing to surrender the first postulate, and has himself altered the second. As it stands now it must be admitted that the continuity of the germ-plasm is an interrupted continuity with the appearance of every inherited change; the continuity is theoretical, not actual, and the stability of the germ-plasm is not absolute but of a high degree. We can thus see in the story of this original theory of heredity the lighthouse value of the _pharos_ of Ptolemy II. [26] Romanes, _Examination of Weismannism_, p. 115. “It is doubtful if anything better as to Weismann’s theory of heredity can be said to-day than Romanes said in 1893, and inasmuch as these two latter or distinctive postulates are not needed for Weismann’s theory of heredity, while they are both essential to his theory of evolution, I cannot but regret that he should have thus crippled the former by burdening it with the latter. Hence my object throughout has been to display, as sharply as possible, the contrast that is presented between the brass (“iron” preferably) and the clay in the colossal figure which Weismann has constructed. Hence also my emphatic dissent from his theory of evolution does not prevent me from sincerely appreciating the great value which attaches to his theory of heredity. And although I have not hesitated to say that this theory is, in my opinion, incomplete; that it presents not a few manifest inconsistencies, and even logical contradictions; that the facts on which it is founded have always been facts of general knowledge; that in all its main features it was present to the mind of Darwin, and distinctly formulated by Galton; that in so far as it has been constituted the basis of a more general theory of organic evolution it has proved a failure; such considerations in no way diminish my cordial recognition of the services which its distinguished author has rendered to science by his speculations upon these topics. For not only has he been successful in drawing renewed and much more general attention to the important questions touching the transmissibility of acquired characters, the causes of variation, and so on; but even those parts of his system which have proved untenable are not without such value as temporary scaffoldings present in relation to permanent buildings. Therefore, if I have appeared to play the _role_ of a hostile critic, this has been only