62 R. A. Emerson 
A single progeny (table 8, group 3, page 126) from a selfed parent 
heterozygous for yellow endosperm, contained purple, sun red, brown, 
and green plants, totaling 63, in the relation 35:15:6:7. These four 
color types are expected to occur in a total of 64 in the relation 36:12:12:4 
from a selfed plant of the genotype AaB B Pl pl. The observed deviation 
from expectation might occur by chance once in nine trials, P equaling 
0.11. Theoretically, the green plants of this lot, a B pl, are differentiated 
from the browns, a B Pl, by the same factor pair, Pl pl, that differentiates 
the sun reds, A B pl, from the purples, A B Pl. If this is true, the 
same linkage relations should exist for yellow endosperm with the 
brown-green lot as with the purple-sun-red lot. From yellow seeds there 
came 29 purples and 8 sun reds, and from white seeds 6 purples and 7 
sun reds. Such a distribution should be very closely realized (2? = 0.97) 
from 30 per cent crossing-over between Y y and Pl pl. The yellow seeds 
produced also 5 brown and 3 green plants, and the white seeds 1 brown 
and 4 green plants. While the number of individuals is too small to give 
a reliable indication, it is of interest to note that the coefficient of asso- 
ciation (Collins, 1912) calculated from the series 5:3:1:4, or 0.739, is 
practically that calculated from 26 per cent of crossing-over. In so far 
as these records go, therefore, they support the assumption that brown 
and green in this lot are differentiated by the same factor pair as are 
purple and sun red, and thereby support the hypothesis under test. 
A plant heterozygous for the three plant-color pairs Aa, Bb, Pl pl, 
and for Yy, backcrossed with a white-seeded green plant of type VIc, 
ab ply, gave the six color types, purple, sun red, dilute purple, dilute 
sun red, brown, and green, in the numerical relation 10:13:17:11:9:33 
(table 6, page 124), which is a close fit (P = 0.61) to the expected relation, 
1:1:1:1:1:3. From yellow seeds the resulting series was 8:6:13:2:7:17, 
and from white seeds it was 2:7:4:9:2:16. When the classes having 
A Pl, purple and dilute purple, were lumped together, and similarly 
those having A pl, sun red and dilute sun red, the yellow seeds gave 21 
plants with Pl and 8 with pl, while the white seeds gave 6 with Pl and 
16 with pl. Of these 51 plants, there were 14 in the crossover classes, 
or a percentage of crossing-over of about 27.5 + 4.1, approximately the 
same as in the cases cited above. In this lot there are theoretically three 
kinds of greens, a B pl, ab Pl, and ab pl, one of which has Pl and two 
of which have pl, while all the browns, a BPI, have Pl. If there be 
