NILSSON'S DISCOVERY 105 



at Svalof, and equally valuable for practice and for science, 

 was that of the almost astonishing richness in elementary 

 species among our agricultural crops. Every cultivated 

 species seems to embrace something like a hundred of them, 

 and the cereals were found to include even several hundreds 

 in each of the older species. Moreover the differences 

 between these elementary forms are so great that they cover 

 nearly the whole field of the wants of the practical agricul- 

 turist, or, in other words, by carefully searching the field, 

 in almost every case a plant may be found which complies 

 with the ideal sought for. From such a plant a pure and 

 constant race may be derived without other means than 

 that of isolating and multiplying its progeny. No special 

 culture and no repeated selection is needed, the only care 

 being to protect the race against vicinism. On the basis 

 of these facts Nilsson has founded an elaborate method of 

 selecting original plants for his pedigree-cultures and of com- 

 paring their value for practical purposes. But though this 

 process is now the prominent part of his work, it has no 

 direct bearing upon the signification of the methods of 

 Rimpau and other German breeders, and so we may leave 

 it here out of consideration. 



Our explanation of Rimpau's method now loses its hypo- 

 thetical aspect. For since it is proven that the ordinary rye- 

 fields contain hundreds of elementary species, and among 

 them many of superior quality, it is clear that Rimpau must 

 have had an assemblage of such types in his original hand- 

 ful of selected ears. To him they may have seemed alike, 

 but they must have been in reality of very different value. 



His slow process of selecting must have singled out in 

 the long run, the very best one from among them. Once 

 isolated, this type yielded a constant race, which became 

 independent of all further selection. 



The German breeding process has always been one of the 



