782 Fluctuations 



The pollen falls from the male spikes on the 

 ears of the same plant, but also is easily blown 

 on surrounding spikes. In order to get the 

 required amount of seed it is necessary in our 

 climate to encroach as little as possible upon 

 free pollination, aiding the self-pollination, 

 but taking no precautions against intercross- 

 ing. It is assumed that the choice of the best 

 ears indicates the plants which have had the 

 best pollen-parents as well as the best pistil- 

 parents, and that selection here, as in other 

 cases, corrects the faults of free intercrossing. 

 But it is granted that this correction is only a 

 slow one, and accounts in a great degree for the 

 slowness of the progression. Under better cli- 

 matic conditions and with a more entire isola- 

 tion of the individuals, it seems very probable 

 that the same result could have been reached 

 in fewer generations. 



However this may be, the fact is that by re- 

 peated selection the strain can be ameliorated 

 to a greater extent than by a single choice. This 

 result completely agrees with the general expe- 

 rience of breeders and the example given 

 is only an instance of a universal rule. It has 

 the advantage of being capable of being re- 

 corded in a numerical way, and of allowing a 

 detailed and definite description of all the suc- 

 ceeding generations. The entire harvest of all 



