THE 



AMERICAN NATURALIST 



Vol. XLVI November, 1912 No. 551 



THE MENDELIAN NOTATION AS A DESCRIP- 

 TION OF PHYSIOLOGICAL FACTS 



PROFESSOR E. M. EAST 

 Bussey Institution, Harvard University 



As I understand Mendelism 1 it is a concept pure and 

 simple. One crosses various animals or plants and re- 

 cords the results. With the duplication of experiments 

 under comparatively constant environments these re- 

 sults recur with sufficient defmiteness to justify the use 

 of a notation in which theoretical genes located in the 

 germ cells replace actual somatic characters found by 

 experiment. This is done wholly to simplify the descrip- 

 tion of the experimental results. If one finds that the 

 expression DR X DR = 1DD + 2DR + 1RR adequately 

 represents the facts in numerous breeding experiments, 

 he is then able to use the knowledge and the expression 

 in predicting the results of other similar experiments. 

 Mendelism is therefore just such a conceptual notation 

 as is used in algebra or in chemistry. No one objects to 

 expressing a circle as % 2 -\-y 2 = r 2 . No one objects to 



J I do not speak here of the new biological facts discovered by Mendel 

 or by his followers. Facts are always facts. Alternative inheritance and 



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