202 Albimsm in Maize 



families. Two of these progenies' consisted only of green plants ; three 

 consisted of green plants and pure white ones in the ratio 3"2 : 1 ; three 

 were composed of green plants and j^ellowish-white ones in very nearly 

 the three-to-one ratio ; and three progenies yielded green plants, yellow- 

 ish-white ones, and pure white ones in a pro])()i-tion closely approximating 

 the 9:3:4 ratio. Theoretically the individuals of the four classes of F^ 

 plants should occur in equal numbers. Of the eleven self-pollinated 

 Fy ears tested, three classes were represented by three each and one 

 class by two. This result is as near the theoretical expectation as 

 would be possible in a test of eleven ears. 



Thus from the study of crosses in the foregoing description, between 

 plants of a family in which pure white seedlings occur and those of 

 a progeny where yellowish-white ones are found, it appears that the 

 production of normal green may be due to the presence of at least 

 two factors : in the absence of one the plant is pure white, while if 

 the other be absent the plant is yellowish-white, often becoming 

 greenish and occasionally, after a time, fully green. 



Further tests have been made with the yellow-green plants (PI. VIII, 

 fig. 7) described by Emerson (10). In this category the seedlings have 

 the normal green colour at first, but later the leaves turn a distinct 

 yellowish colour and because of the striking resemblance to the "golden" 

 varieties of some of the horticultural plants the term " golden " will 

 hereafter be used in describing this type. 



In the summer of 1912 the F.> of a cross between a green plant and 

 a golden one yielded 40 green jjlants and 11 golden ones. Two of the 

 green plants were crossed with pure golden plants and in one of these 

 crosses the green plant was heterozygous, as shown by the fact that the 

 progeny resulting from the cross consisted of 50 pei' cent, green plants 

 and 50 per cent, golden ones. 



None of the F^ plants showed any of the golden colour, thus 

 indicating that green is completely dominant. Eight of the F^ plants 

 were self-pollinated. It would be expected that seed from each of the 

 Fi ears would yield a progeny consisting of 75 per cent, green plants 

 and 25 jDer cent, golden plants, but the progeny from one ear was 

 composed entirely of green plants. Many seedlings of this progeny 

 were destroyed by mice and only 12 plants grew to the age of eight 

 weeks, or the time when the golden individuals can usually be identified. 

 Since only one out of four plants should be of the golden type, it is 



1 One of these progenie.s (No. 3iOo) consisted of too few individuals to show con- 

 clusively that it was of the pure green type, yet it is probable that such was the case. 



