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 ^o 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 



