42 BULLETIN 1489, IT. S. DEPARTMENT OF AGRICULTURE 
masked. As the program advances, the stocks segregate for fewer 
striking characters and opportunity is presented to select the better 
functioning (or to eliminate the less efficient) lines. Finally, the 
selected lines are crossed and the crosses of one kind or another are 
compared to afford a basis for the final selection of those selfed lines 
which produce the best hybrid combination. 
An idea of the opportunity for selection that exists in the later 
phases of the breeding program may be had from Plates 10, 11, and 
12, which illustrate representative ears and plants of Cereal Investi- 
gations (C. I.) No. 228. This number was given a single open- 
pollinated ear of the Lancaster Surecrop variety of corn. Nine 
plants from kernels on this ear were self -pollinated in 1920. The 
resulting ears were the parent stocks for nine families of self eel 
lines, one of which (No. 8) was discarded. The pedigree numbers 
of family No. 4 are shown in Figure 7. The breeding ears for 14 
lines from these 8 families planted in 1926 are shown in Plate 10. 
Representative plants of some of the lines and of crosses between 
them are shown in Plates 11 and 12. That the opportunity for 
selection is not limited to the selfed lines is shown clearly by the 
variation that exists among the crosses. The plants in Plate 11 have 
been arranged to show particularly the uniformity with which some 
lines may influence their crosses. The plants in Plate 12 are arranged 
to show primarily the relative size of the parent lines and their 
crosses in comparison with a representative open-fertilized (O. F.) 
plant of the Lancaster variety. 
Positive selection for relatively simple characteristics may be prac- 
ticed in the selfed lines with reasonable assurance that if lines breed- 
ing true are obtained some of the crosses between these lines also will 
exhibit the desired characteristic. Because of the importance of this 
concept it is desirable to illustrate it with a hypothetical case. This 
may be used also as an example of why selection within selfed lines 
is sO much more efficient than mass selection in modifying qualitative 
characters. 
Aleurone color, the mode of inheritance of which already has been 
described (p. 11), affords a convenient example. Assume that a 
variety of corn is homozygous for the factors A A, Pr Pr, and i a, and 
heterozygous for the factors C c and R r. As all of the plants are 
alike for the first three factor pairs, they need not be considered 
further, the aleurone color of the kernels being determined by the 
factors c and R r. The following nine classes of kernels would be 
produced in such a variety: 
Purple aleurone: (1) O C R R, (2) C C R r, (3) C c R R, (4) c R r. 
Colorless aleurone: (5) C G r r, (6) Cor r, (7) o c r r, (8) c c R r, (9) 
c c R R. 
Consider now the results of specific selection for purple aleurone, 
colorless aleurone being assumed undesirable. Purple kernels from 
each of a number of ears would be planted an ear to a row, and some 
of the resulting plants in each row would be self -pollinated. Three 
classes of ears would be obtained: (a) Ears with all kernels purple, 
from seed of class 1; (b) ears having three kernels with purple to 1 
kernel with colorless aleurone, from seed of classes 2 and 3: and (c) 
ears having 9 kernels with purple aleurone to 7 with colorless aleu- 
rone, from seed of class 4. The seed on each ear having all kernels 
