Puant Cotors In Maize 63 
assumed 25 per cent of crossing-over between Yy and PI pl, equivalent 
to a 3:1:1:3 gametic series, yellow seeds should give 3 brown to 5 green, 
and white seeds 1 brown to 7 green, as shown below: 
Yellow White 
LEVRONWHOL 0) JERR El hie os SA Bia Gn ORE Re A Te ee 3 1 
SE RECT Bog DU eos te) ap asics. ts 3 aly ac sy eck asa 2 1 3 
Gieen; C012 ee ne een 3 il 
CURE, GD FOCI ate etre aaa en Oe 1 3 
5 7 
The yellow seeds actually gave 7 brown to 17 green and the white seeds 
2 brown to 16 green, which is a close fit to the calculated relation, 3:5: 
1:7 (P=0.59). In this case as in the others, then, the linkage relations 
between Y y and PI pl afford additional support for the belief that the 
several color types actually bear to one another the relation assumed in 
the assignment of hypothetical genetic formulae (page 32). 
Linkage of plant color with leaf type-—It has been known for some 
years that a leaf type termed liguleless (Emerson, 1912) is linked with 
the factor pair that differentiates sun red from dilute sun red. As an 
illustration of this, two backcross progenies, 8250 and 8253, with a total 
of 145 sun red and 147 dilute sun red plants, may be cited. These progenies 
came from a cross of normal-leaved sun red, A B pl Lg, with liguleless- 
leaved dilute sun red, A 6 pl lg, backerossed with liguleless dilute sun red. 
Of the normal-leaved plants 104 were sun red and 41 were dilute sun red, 
while of the liguleless-leaved plants 48 were sun red and 99 were dilute 
sun red. The non-crossovers were to the crossovers as 203:89, or a per- 
centage of crossing-over of 30.5. Since the factor pair that differentiates 
sun red from dilute sun red has been assigned the symbol B b, the linkage 
noted here is evidently between B b and Lg lg. 
Six progenies from backcrosses of heterozygous nermal-leaved purples 
with liguleless dilute sun reds gave purples, sun reds, dilute purples, and 
dilute sun reds in the relation 197:177:178:167, which is not far from the 
equality expected, P equaling 0.46. Among the normal-leaved plants, 
the four color types occurred in the relation 123:117:47:55, and among 
the liguleless-leaved plants in the relation 74:60:131:112. Evidently the 
purples bear the same relation to the dilute purples as the sun reds do to 
3 
