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Indiana University Studies 



Castle says his results show the multiple factor hypothesis 

 to be untenable, yet in our work we know there are multiple 

 factors present. 



Discussion 



The theory of natural selection is rightly attributed to 

 Darwin, as he was the first to develop it to a point where it 

 was a recognizable and acceptable theory. Darwin supported 

 his theory by a large mass of facts drawn largely from the 

 production of domestic plants and animals, and in the collec- 

 tion of his data relied mainly on the statements of breeders. 

 His theory was very generally accepted inasmuch as no one 

 questioned his data and the theoretical discussion seemed very 

 plausible. It was really the first sound piece of logical reas- 

 oning backed by an accumulation of facts presented in favor 

 of evolution and the method of evolution. The evidence 

 seemed overwhelming and the explanation so simple that many 

 wondered why they had not thought of it themselves. At 

 any rate, the people accepted the theory, partly perhaps, 

 because the time was ripe for the acceptance of an evolution 

 theory, but primarily, because of the forcible manner in which 

 Darwin presented his argument. 



No one seriouslj^ attacked the evidence and offered some- 

 thing to take its place until Galton ('89) compared fluctuat- 

 ing variations to the oscillations of a polyhedron on one face, 

 and discontinuous variations to the overturn of the poly- 

 hedron on to a new face, and suggested that species may 

 arise from such discontinuous variations. Bateson ('94) in 

 his ''Materials for the Study of Variations", argues for the 

 fixity of species. While he is cautious as to his generalizations, 

 yet, I think, he means to imply that the evidence for evolu- 

 tion by means of fluctuating variations is far from satis- 

 factory, and that discontinuous variations may give a more 

 plausible and acceptable explanation. 



Following the work of Galtpn and Bateson a number of 

 things happened in rapid succession. Mendelism was redis- 

 covered in 1900. DeVries developed his "Mutationstheorie" 

 in 1901, and Johannsen the pure line theory in 1903. Kor- 

 schinsky ('01), in a review of the horticultural literature, 

 showed that where the origin of a variety is known and 

 recorded, the origin, in most cases, was sudden. The work 

 of Nilsson and Burbank demonstrated that, from their ov/n 



