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 dis- 

 orders of various kinds — albinos, brachydactyls, cretins, dwarfs, 

 freaks, giants, hermaphrodites, imbeciles, Jukes, Kallikaks, luna- 

 tics, 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 re- 

 ceived 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 in- 

 dictment. Nevertheless, I am going to ask your indulgence, for a 

 moment, since this slightly malicious statement should not be al- 

 lowed to pass unchallenged, both because it is inaccurate, and be- 

 cause, 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 re- 

 place it) with the new wood of Mendelian genetics. Hence, I 

 think, originates the criticism referred to. 



It is true that the student of Mendelian heredity does not often 

 trouble himself about the nature of the character that he studies. 

 He is concerned rather with its mode of inheritance. But the 

 geneticist knows that opposed to each defect-producing ele- 



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