PLANT CoLors IN Maize 61 
color. The data suggest irregularities or complexities which cannot be 
straightened out until more definite. information is at hand with regard 
to the two or more factor pairs concerned in the development of yellow 
endosperm.® Only such data are presented here as are necessary to 
show the relations of the several plant-color types to endosperm color. 
* A single progeny recorded in table 27, group 2 (page 140), was made 
up of 74 purple and 75 sun red plants. The lot resulted from a cross 
of a white-seeded sun red plant with a dilute purple plant which was 
heterozygous with respect to both yellow endosperm and plant color. The 
yellow seeds produced 58 purple and 20 sun red plants, and the white 
seeds produced 16 purple and 55 sun red plants. The yellow-seeded 
sun reds and the white-seeded dilute purples are known to be the crossover 
classes. The ratio of non-crossovers to crossovers is 113:36, and the 
percentage of crossing-over, therefore, is 24.2. Evidently a factor pair for 
yellow endosperm, Y y, is linked with the factor pair that differentiates 
purple from sun red. In accordance with the hypothesis under test, this 
plant-color factor pair is Pl pl— purple=A B Pl, and sun red=A B pl. 
Two other progenies (table 26, group 1, page 139) had a total of 116 
dilute purple and 42 dilute sun red plants. The selfed parent plants 
were heterozygous tor yellow endosperm as well as for plant color. The 
yeliow seeds gave 99 dilute purple and 17 dilute sun red plants, and the 
white seeds gave 17 dilute purple and 25 dilute sun red plants. This 
F, distribution, as shown below, is very close to expectation ( x? = 0.26) 
on the basis of 25 per cent of crossing-over between the factor pair Yy 
and the pair that differentiates dilute purple from dilute sun red. It seems 
likely, therefore, that the same plant-color factors, Pl pl, are concerned 
here as in the progeny consisting of purples and sun reds. This is in 
keeping with the theoretical genotypes, A b Pl and A b pl, assumed for 
dilute purple and dilute sun red, respectively. The comparison between 
the observed F 2 distribution and that calculated on the basis of 25 per 
cent of crossing-over follows: 
MNSCEVEC eee. oes oe 99 iL7/ 17 Dy eels 
Malenlated 2. ko ci ahs 102 17 17 Da thee ad 90) 
BDinherence <.. 285 2S ec ees —3 0 0 +2 —] 
5 This problem is being investigated by Dr. E. G. Anderson. 
