PLANT BREEDIXG 315 



stations, the principal steps of the operation are here 

 given in the barest outline, omitting many most impor- 

 tant details.^ 



(1) Ten thousand large, sound kernels of a single good 

 variety of wheat are selected, planted in hills, and each 

 hill numbered. About ninety-five per cent of the poorer 

 plants are rejected as they mature. The heads of each of 

 the chosen plants are put together in an envelope and 

 preserved. When thoroughly dry the product of each 

 plant is weighed, and only a few of the heaviest groups of 

 heads are kept for seed. 



(2) The second year about a hundred of the seeds 

 of each mother-plant are planted in a group to which is 

 given a special designating number (hundred-group or 

 centgener). Heads of several of the best plants in each 

 hundred-group are reserved for seed. The total produced 

 by each hundred-group is weighed to enable the experi- 

 menter to estimate the comparative value of the mother- 

 plants of (1). 



(3) The third year the process gone through in the 

 second year is repeated. 



(4) The fourth year the same process is repeated. 



(5) The fifth year the most promising varieties are 

 planted in small fields in the ordinary way. Those varie- 

 ties which yield abundantly in the field and turn out well 

 in the millmg tests applied to the harvested grain are 

 distributed among farmers for seed-wheat. 



A new variety can soon be introduced over an immense 

 territory. It is estimated that in fifteen years from the 



1 See University of Minnesota, Agricultural Experiment Station, Bulletin 

 jpb. 62 ; and United States Department of Agriculture, Division of Vegetable 

 Physiology and Pathology, Bulletin No. 29. 



