[58] _The Germ-plasm_, p. 431. [59] _Variation_ &c., vol. i. p. 398. [60] _Ibid._, vol. ii. p. 242. [61] _Nature_, May 11, pp. 28-29.—In 1891-2 Professor Hartog furnished a criticism of Weismann’s theory of Heredity (_Nature_, vol. 44. p. 613, and _Contemporary Review_, July, 1892). Although disputed at the time by some of Weismann’s followers in England, this criticism was one of unquestionable cogency, and has now been recognized as such by Weismann himself (_The Germ-plasm_, pp. 434-5). The main point of the criticism had been missed by previous critics of Weismann, and consisted in revealing an important “difficulty” inherent in the structure of the theory itself. How far this criticism had the effect of causing Professor Weismann to abandon his theory of variation being exclusively due to amphimixis, as Professor Hartog appears to think (_Nature_, May 11, 1893, p. 28), is immaterial. But it must be observed that as far back as February, 1890, Professor Weismann in his answer to Professor Vines’ criticism wrote the passage already quoted on page 152. [62] It is almost needless to say that no fault is to be found with Weismann for having thus reversed his opinion touching one of his fundamental postulates. Consistency is no merit in a man of science; and least of all where matters of such high speculation are concerned. I think, however, that it is open to question whether an author of any kind should suffer an elaborate system of theories to be published and translated, at the very time when he is himself engaged in producing another work showing the untenable character of their basal premises. At any rate, it would have saved his English readers no small trouble and confusion, if Weismann had added notes to the translations of his essays on _Polar Bodies_, on _The Significance of Sexual Reproduction_, and on _Amphimixis_, to the effect that he had abandoned some of their most distinctive features before the translations had gone to press. [63] See especially pp. 86-89. All that is there said about the unicellular organisms is not, in the present connexion, affected by Weismann’s change of view with regard to them. We have only to substitute “primordial” or “protoplasmic” for “unicellular,” and nearly all the points of the criticism remain. [64] Professor Weismann has now considered more fully than heretofore the phenomena of bud-variation (_The Germ-plasm_, pp. 439-442); but as he continues (though with diffidence) to take substantially the same view of them as that which I have already quoted on pp. 95-96, it is needless for me to re-discuss the matter here.