46 PLANT-BREEDING 



single mother plants, he compared their yielding capacity 

 in the next generation. In order to have an easy standard 

 of comparison, he sowed a hundred kernels of each and 

 thence derived the name "centgener power" for the index 

 of productiveness of the single races isolated in this way. 

 He claims to have obtained varieties which, under the same 

 culture and treatment, will yield 10 to 15 per cent more than 

 the old unpurified wheats of Minnesota. 



The same principle of judging the parent plant by the 

 average value of its progeny, and of founding selection on 

 this mark, has been applied by von Lochow to rye, and it is 

 said that his new race of "Rye of Petkus" as it is called, 

 excels all the older improved German kinds of rye, and that 

 even the celebrated rye of Schlanstedt may soon prove to be 

 surpassed by it. 



We have given a survey of the most prominent and most 

 renowned principles in the breeding of cereals, and have 

 only to complete our list by a description of the method 

 followed by the larger number of the breeders of Germany. 

 Among them, Heine, Drechsler, Mokry and Rimpau may 

 here be named. Their purpose was to improve the ordinary 

 varieties by continuous selection, directed according to 

 distinct views and requirements. They considered the 

 starting points of the English breeders as accidental sports 

 w r hich no doubt might be made use of with advantage, but 

 would only yield improvements of an inferior rank. 



Two features are essential to this German method. 

 First the initial choice, and secondly the slow and gradual 

 improvement by selection. In this first choice they did not 

 try to obtain deviating types and to isolate them from 

 among the throng. Quite on the contrary, they selected the 

 best representatives of the variety they wished to improve, in 

 order to be sure to retain all of its good features in the new 

 race and to combine them with the new characters which 



