SOME POSSIBLE BEARINGS OF GENETICS ON PATHOLOGY THOMAS HUNT MORGAN Professor of Experimental Zoology, Columbia University, New York. Middleton Goldsmith Lecture delivered before the New York Pathological Society on February 3, 1922. PRESS OF THE NEW ERA PRINTING COMPANY LANCASTER, PA. 1922 SOME POSSIBLE BEARINGS OF GENETICS ON PATHOLOGY THOMAS HUNT MORGAN, PROFESSOR EXPERIMENTAL ZOOLOGY, COLUMBIA UNIVERSITY. It has been pointed out in derision that modern genetics deals, for the most part, with the inheritance of abnormalities and disorders of various kinds—albinos, brachydactyls, cretins, dwarfs, freaks, giants, hermaphrodites, imbeciles, Jukes, Kallikaks, lunatics, morons, polydactyls, runts, simpletons, twins, and Zeros: in a word, with pathological phenomena in a very broad sense. This statement, intended as a reflection on genetics, carries with it an implication that a study dealing with such material cannot be of first rate importance. Such condemnation will probably be received by pathologists with the kind of smile it deserves, and I feel that I am not likely to be called upon here to answer such an indictment. Nevertheless, I am going to ask your indulgence, for a moment, since this slightly malicious statement should not be allowed to pass unchallenged, both because it is inaccurate, and because, even were it true, the result of such work might still be of more importance than its critics seem to realize. The source of this criticism is not without significance. It comes almost always from those whose interests lie in the field of evolution—in the old-fashioned use of that word. Now the articles of all evolutionary platforms include a plank about heredity. This plank is for the most part an ancient article that has been worn pretty thin. It is difficult to replace it (or at least it is supposed to be difficult to replace it) with the new wood of Mendelian genetics. Hence, I think, originates the criticism referred to.