Whatever answer the future may give to that question, it is clear from this moment that every case which obeys the Mendelian principle is removed finally and irretrievably from the operations of the Law of Ancestral Heredity. At this juncture Professor Weldon intervenes as a professed exponent of Mendel’s work. It is not perhaps to a devoted partisan of the Law of Ancestral Heredity that we should look for the most appreciative exposition of Mendel, but some bare measure of care and accuracy in representation is demanded no less in justice to fine work, than by the gravity of the issue. Professor Weldon’s article appears in the current number of _Biometrika_, Vol. I. Pt. II. which reached me on Saturday, Feb. 8. The paper opens with what purports to be a restatement of Mendel’s experiments and results. In this “restatement” a large part of Mendel’s experiments--perhaps the most significant--are not referred to at all. The perfect simplicity and precision of Mendel’s own account are destroyed; with the result that the reader of Professor Weldon’s paper, unfamiliar with Mendel’s own memoir, can scarcely be blamed if he fail to learn the essence of the discovery. Of Mendel’s conception of the hybrid as a distinct entity with characters proper to itself, apart from inheritance--the most novel thing in the whole paper--Professor Weldon gives no word. Upon this is poured an undigested mass of miscellaneous “facts” and statements from which the reader is asked to conclude, first, that a proposition attributed to Mendel regarding dominance of one character is not of “general”[52] application, and finally that “all work based on Mendel’s method” is “vitiated” by a “fundamental mistake,” namely “the neglect of ancestry[53].” [52] The words “general” and “universal” appear to be used by Professor Weldon as interchangeable. Cp. Weldon, p. 235 and elsewhere, with Abstract given below. [53] These words occur p. 252: “The fundamental mistake which vitiates all work based upon Mendel’s method is the neglect of ancestry, and the attempt to regard the whole effect upon offspring produced by a particular parent, as due to the existence in the parent of particular structural characters, &c.” As a matter of fact the view indicated in these last words is especially repugnant to the Mendelian principle, as will be seen. To find a parallel for such treatment of a great theme in biology we must go back to those writings of the orthodox which followed the appearance of the “Origin of Species.”