304 Maine; agriculturai, experiment station. 1910. 



5. The Type II corn selected in 1907 was grown in a new 

 locality (for it) in 1908. Under these circumstances no general 

 gain "in earliness was found, though there were individual rows 

 which were distinctly early for that type of corn. The "new- 

 place" effect appeared quite to outweigh the effect of selection 

 so far as the general Type II crop in 1908 was concerned. 



6. There was in general a marked improvement in respect 

 to conformation of ear (including shape, fineness of kernel and 

 quality of tip and butt) following the first year's selection. 

 This gain has been maintained where the corn has been grown 

 in localities to which it is well adjusted. A study of the sweet 

 corn in the field in 19 10 confirms this conclusion by another 

 year's work. 



7. Two years' ear-to-row tests furnish no evidence that there 

 is any close association or correlation between the size or con- 

 formation of the seed ear and the yield of corn obtained from 

 it upon planting. The large, well tipped, and beautifully shaped 

 ear is as likely as not to prove a poor yielder when planted. 

 This result means that the external, visible characters of the 

 ear are a very unreliable indication of its probable worth for 

 seed purposes. This is the same result to which all recent 

 experimental studies of breeding appear to lead. 



8. The present experiments point clearly to the conclusion 

 that in any attempt to improve corn by selection the fundamental 

 datum must be the performance of the rozv planted on the ear- 

 to-row system (i. e., the performance of the progeny of an ear) ■ 

 rather than the individual ear or plant. In other words, the 

 selection of the best individual cannot alone be depended upon 

 for improvement. A poor genotype may often yield a good 

 individual. The function of selection must be to discover and 

 separate the desirable genotypes from the poor ones. 



In making this statement it is not intended to advocate the 

 isolation (whether by extreme pedigree selection or by hand 

 pollination) of a single pure line or homozygote strain as the 

 thing to be aimed at in practical corn breeding. Shull and East 

 (cf. infra), who have isolated pure lines of maize, have both 

 found that such corn yields very poorly and is altogether unde- 

 sirable from the practical standpoint, lacking particularly in 

 vigor. Apparently vigor and yielding quality in maize depend 



