CHAPTER III 



The Mendelian Principles of Heredity and 

 Their Bearing on Sex 



The modern study of heredity dates from the year 

 1865, when Gregor Mendel made his famous discoveries 

 in the garden of the monastery of Brunn. For 35 

 years his paper, embodying the splendid results of his 

 work, remained unnoticed. It suffered the fate that 

 other fundamental discoveries have sometimes met. 

 In the present case there was no opposition to the 

 principles involved in Mendel's discovery, for Darwin's 

 great work on ''Animals and Plants" (1868), that dealt 

 largely with problems of heredity, was widely read and 

 appreciated. True, Mendel's paper was printed in 

 the journal of a little known society — the Natural 

 History Society of Brunn, — but we have documentary 

 evidence that his results were known to one at least of 

 the leading botanists of the time. 



It was during these years that the great battle for 

 evolution was being fought. Darwin's famous book on 

 ''The Origin of Species" (1859) overshadowed all else. 

 Two systems were in deadly conflict — the long-ac- 

 cepted doctrine of special creation had been challenged. 

 To substitute for that doctrine the theory of evolution 

 seemed to many men of science, and to the world at 

 large, like a revolution in human thought. It was in 

 fact a great revolution. The problems that bore on the 



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