102 PLANT-BREEDING 



cultures of the Minnesota Experiment Station, and I may 



assume that their leading principles and practical results 



are well kno\\Ti. But I wish to point out, that exactly in 



the principle of sowing the seeds of individual selected plants 



separately. Hays gained a distinct advantage over the slow 



process of Rimpau and the other German breeders. He 



found, by his method, that the isolated strains are at once 



constant and pure. They had only to be multiphed in 



order to give a new race. Of course, the different mother 



plants had to be compared in their progeny, and among a 



large number of such new pedigree-races only one or two 



were found to be of the very best. The remainder had to 



be rejected, and only those few most excellent ones could be 



introduced with advantage into the field-cultures of the 



state. 



If now we compare this principle of Hays with the 

 method of Rimpau we find that the American breeder by 

 one single choice isolated the very best strains and observed 

 them to be constant and pure. The German breeder, on 

 the other hand, by selecting a number of ears, must have 

 gotten an impure race, and needed a long succession of 

 years and a constantly repeated selection to attain, in the 

 end, the same result. 



Hence we may presume that if Rimpau, in starting his 

 experiments, forty years ago, had had at his disposal our 

 present knowledge of variability, he would have sown the 

 kernels of his selected ears separately and selected at once 

 among the resulting strains the very one which now bears 

 the name of his farm. No continuous culture and repeated 

 selection would have been needed, and the seemingly slow 

 and gradual improvement of a race by selection would have 

 been avoided. 



The proof of this assertion can be given, as has been 

 said in the beginning, by means of the magnificent experi- 



