CHAPTER XVII 



THE ORIGIN OF THE MENDELIAN MODE OF INHERITANCE 



It is a very important raatter to determine whether, 



as some hold, MendeKan heredity is a fundamental 



process the true understanding of which will render 



all other phases of heredity intelligible, or whether, 



as others believe, it is an anomalous phase of heredity 



which is restricted to a small group of characters 



belonging chiefly to domesticated animals and plants. 



For if the latter is the case, the investigation of 



Mendelian phenomena can throw no light on the 



problem of the relation between successive generations 



of organisms, nor help to elucidate the nature of the 



processes to which evolution is due. The chief 



exponent of the view that Mendelian inheritance is 



merely an anomalous phase of heredity is Dr. Archdall 



Reid, whose views on this subject are expressed in 



his recent book, " The Laws of Heredity," to which the 



reader is referred for a full exposition of this view. 



Perhaps the simplest way of expressing this view is 



to say that, according to it, we have begun to read 



the series of phenomena and of hypotheses, which 



extends from the first to the sixteenth chapter in 



this book, at the wrong end. We have taken the 



simple Mendelian phenomenon as the starting-point, 



and have finished up by interpreting the inheritance 



and nature of sex in the light of it ; whereas, according 



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