156 Plant-Breeding 



semination of the mendelian ideas in America are the in- 

 struction given by Webber and others in the Graduate 

 School of Agriculture at Columbus, Ohio, in the summer 

 of 1904 and the prolonged discussion before the Interna- 

 tional Conference on Plant Breeding at New York in the 

 fall of 1902. Since that time many articles on the subject 

 have appeared from our scientific press. 



Mendel's work is important because it cuts across many 

 of the current notions respecting hybridization. As 

 de Vries' discussions call a halt in the current belief re- 

 garding the gradualness and slowness of evolution, so 

 Mendel's call a halt in respect to the common opinion 

 that the results of hybridizing are largely chance, and that 

 hybridization is necessarily only an empirical subject. 

 Mendel found uniformity and constancy of action in 

 hybridization, and to explain this uniformity he proposed 

 a theory of heredity. 



One of the most significant points connected with 

 Mendel's work is the great care he took to select plants 

 for his experiments. He thought that hybridism is a 

 complex and intricate subject, and that, if we are ever to 

 discover laws, we must begin with the simplest and least 

 complicated problems. He was aware of the general 

 opinion that the most diverse and contradictory results are 

 likely to follow any hybridization. He conceived that 

 some of this diversity may be due to instability of parents 

 rather than to the proper results of hybridizing. He also 

 saw that he must exclude all inter-crossing in the progeny. 

 Furthermore, the progeny must be numerous, for, since 

 incidental and aberrant variation may arise in the plants, 

 it is only by a study of averages of large numbers that the 



