NILSSON'S DISCOVERY 77 



ered as wholly established. At once they were raised to 

 the rank of an exclusive method. Of course, the existing 

 cultures could not easily be given up, but they could be 

 rapidly diminished. After three years, almost all the exper- 

 iments were of the separate-culture sort, and of older va- 

 rieties only a small number were kept, and destined to afford 

 the material for a comparison of the novelties with the types 

 they were called upon to replace. Since that time, the se- 

 lection of crowds, or even of small groups of heads, has com- 

 pletely been abandoned at Svalof, and all the numerous new 

 sorts which the station has since introduced into the trade 

 are derived each from a single individual. Consequently, 

 they are absolutely pure, and purity is for them such a matter 

 of course that often it is hardly mentioned at all. 



Pure races, however, are by no means the sole, or even 

 the first, requisite of the farmer. Above all, they must have 

 better qualities and yield a richer harvest than the ordinar}' 

 varieties. Thus the question arose whether the separate- 

 cultures would satisfy in this respect. But even here they 

 were found to surpass all expectations. Of course, of two 

 thousand types, all cannot be excellent. But manifestly 

 this is not at all necessary. It is quite sufficient, if among 

 them, some few are found having really excellent qualities. 

 A careful comparison of the famihes of the year 1893 

 showed that their mutual differences WTre much greater 

 than could be surmised from the amount of variabihty ob- 

 served in the fields at the time of selection. Moreover, the 

 separate-cultures complied with the most diverse require- 

 ments, some being highly resistant to frost, others to dis- 

 eases, some being suited for hard and others for Hght soils, 

 some being early and others late in ripening, some surpass- 

 ing others by the stiffness of their culms, the length of their 

 ears, the number and size of their grains, and so on. Hard- 

 ly any demand could be pointed out, with which at least 



