CORN BREEDING 27 
rounded butt, well-filled tip, and a high percentage of shelled grain. 
The further considerations of quality and disease resistance also 
warrant selection toward the longer, smoother ear, with fewer rows 
of kernels and thicker kernels. 
There is some evidence that too close selection for any given kind 
of ear may reduce yields by bringing about a condition approaching 
that produced by inbreeding (25). The best plan, therefore, appears 
to be to select sound, well-developed ears of an adapted variety with- 
out trying to make them conform to any very specific type. 
SELECTION FOR PLANT TYPE 
There seem to be no characters of the corn plant that can be classed 
as uniformly advantageous from the standpoint of yield, except those 
indicating normal vigorous development. Thus, larger, leafier 
plants may be more productive in one environment, and smaller, 
less leafy plants may be better under other conditions. In other 
words, the question is one of adaptation rather than of specific form 
or function, and selection should be toward the kind which is adapted 
best to the conditions under which the corn is to be grown. 
A possible exception to this is the tendency to produce more than 
one ear per plant. A number of experiments have shown that pro- 
lific strains, i. e., those having a strong tendency to produce more 
than one ear per plant under fairly good conditions, are inclined to 
be more productive than similar strains that. normally produce but 
one ear per plant (#, 52). The best evidence for this comes from 
comparisons in the Southern States, where a long growing season 
permits larger yields from the individual plants. The flint and 
flour varieties of the North, however, also tend to have more than 
one ear per plant and are extremely efficient in producing grain under 
adverse conditions. The ears are smaller in prolific varieties, and 
the methods of handling the corn crop in the Corn Belt have not 
been conducive to developing adapted prolific sorts. Consequently, 
there is little evidence as to the value of selection for prolificacy in 
this region. With an increased use of mechanical corn pickers such 
A T arieties may be developed, and the evidence from other sections in- 
dicates that they should be more productive than single-eared varie- 
ties. The lack of experimental evidence on this point at the present 
time, however, prevents an unqualified recommendation to select for 
more than one ear per plant in the Corn Belt. 
PLACE OF MASS SELECTION 
The development of practically all of our present varieties of corn 
was achieved by mass selection, and, although progress with this 
method is slow after grosser adaptation has been achieved, there is 
every evidence that it is effective in at least maintaining yields. 
Mass selection unquestionably is the only method of corn improve- 
ment to be recommended for the average individual who does not 
have specific training in plant breeding. More elaborate methods 
will be discussed, but their practice will be restricted largely to 
technical plant breeders working at experiment stations, with large 
seed growers, or with farmers' cooperative associations of one kind 
or another. 
