The only conclusion which most readers could draw from this abstract and indeed from the article it epitomizes, is that Mendel’s discovery so far from being of paramount importance, rests on a basis which Professor Weldon has shown to be insecure, and that an error has come in through disregard of the law of Ancestral Heredity. On examining the paper it is perfectly true that Professor Weldon is careful nowhere directly to question Mendel’s facts or his interpretation of them, for which indeed in some places he even expresses a mild enthusiasm, but there is no mistaking the general purpose of the paper. It must inevitably produce the impression that the importance of the work has been greatly exaggerated and that supporters of current views on Ancestry may reassure themselves. That this is Professor Weldon’s own conclusion in the matter is obvious. After close study of his article it is evident to me that Professor Weldon’s criticism is baseless and for the most part irrelevant, and I am strong in the conviction that the cause which will sustain damage from this debate is not that of Mendel. I. THE MENDELIAN PRINCIPLE OF PURITY OF GERM-CELLS AND THE LAWS OF HEREDITY BASED ON ANCESTRY. Professor Weldon’s article is entitled “Mendel’s Laws of Alternative Inheritance in Peas.” This title expresses the scope of Mendel’s work and discovery none too precisely and even exposes him to distinct misconception. To begin with, it says both too little and too much. Mendel did certainly determine Laws of Inheritance in peas--not precisely the laws Professor Weldon has been at the pains of drafting, but of that anon. Having done so, he knew what his discovery was worth. He saw, and rightly, that he had found a principle which _must_ govern a wide area of phenomena. He entitles his paper therefore “_Versuche über Pflanzen-Hybriden_,” or, Experiments in Plant-Hybridisation. Nor did Mendel start at first with any particular intention respecting Peas. He tells us himself that he wanted to find the laws of inheritance in _hybrids_, which he suspected were definite, and that after casting about for a suitable subject, he found one in peas, for the reasons he sets out. In another respect the question of title is much more important. By the introduction of the word “Alternative” the suggestion is made that the Mendelian principle applies peculiarly to cases of “alternative” inheritance. Mendel himself makes no such limitation in his earlier paper, though perhaps by rather remote implication in the second, to which the reader should have been referred. On the contrary, he wisely abstains from prejudicial consideration of unexplored phenomena. * * * * *