328 GENETICS IN RELATION TO AGRICULTURE 
The Illinois Station experiments have included selection for many 
other characters of the corn plant in more recent years. One of the most 
striking results was obtained by selecting for height of ear on the plant. 
Data on which to base selection were secured by measuring several 
hundred stalks in the oil and protein plots, noting height of ear above the 
ground, total height of stalk, apparent number of internodes below the 
Per Cent of Oil 
enpowrre 1 ran © wo 
96 '97 98 "99 *00 °O1 °02 '03 °04 '05 06 707 "08 '09 10 "11 "12 '13 ‘14 '15 
Year of Selection 
Fic. 133.—Two graphs representing the effects of selection for high and low oil content in 
the Illinois Station corn experiments. (Data from Casile.) 
ear and number of internodes above the ear. Fig. 135 shows the result 
of selecting for high and low ears during five generations. Similar results 
were obtained from selection in the case of position of ear at maturity 
and total yield. 
The striking results of these carefully conducted experiments have 
been cited by various authors as evidence par excellence for the most 
16 
15 
14 
13 
Per Cent of Protein 
"96 '97 '98'99'00 "01 '02 "03 04 °05 '06 "07 '08 '09 10 "11 °12 °13 "14°15 
Year of Selection 
Fic. 134.—Two graphs representing the effects of selection for high and low protein con- 
tent in the Illinois Station corn experiments. (Data from Castle.) 
diverse conceptions of the réle which selection plays in evolution and 
breeding. Thus the earlier allusions of Hopkins and Smith, the discus- 
sion in EK. Davenport’s text on breeding, and the recent treatment by 
Castle all seem to attribute a peculiar creative power to selection which 
meets with a certain “response” on the part of the plant. This is in line 
with the Darwinian idea that all fluctuating variations are heritable and 
that the continuous selection of minor fluctuations in a certain direction 
is always effective in shifting the type. 
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