In view of the inability accurately to determine values by mere outward 

 appearance, together with the fact that yield, representing as it does the 

 product of many factors, may often be accepted as a fair index of the real worth 

 of a sort, Nilsson-Ehle has introduced a special system, in connection with 

 work with wheat and oats, by which yielding tests are resorted to after the 

 third generation as an aid in determining the value of selected cultures. 

 Thus a bulk sample of seed is taken from each of the cultures finally selected 

 in the third generation and sown on a regular preliminary test plot. Such a 

 plot is therefore the common representative of a whole group of fourth genera- 

 tion cultures whose yielding power it is supposed t6 express. By this arrange- 

 ment it is possible to discriminate between whole groups of cultures. After- 

 choosing the most promising groups a number of the best appearing plots 

 within each of these groups is again chosen to provide plants for new pedigrees 

 as well as seed for further yielding tests. This process is continued until the 

 best possible results in the desired direction are obtained. 



In order to make this system more clear the following scheme, devised 

 by Nilsson-Ehle to illustrate the actual course taken in connection with the 

 Pudel X Velvet Chaff wheat crossing, is submitted (50, p. 343) : 



