PLANT BREEDING 315 
stations, the principal steps of the operation are here 
given in the barest outline, omitting many most impor- 
tant details.1 
(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 milling 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 
No. 62; and United States Department of Agriculture, Division of Vegetable 
Physiology and Pathology, Bulletin No. 29. 
