198 Albinism in Maize 



only one of them set an ear. Seed from the self-pollinatetl ear gave 

 26 green plants and 16 which were yellowish- white. This is fully in 

 accord with the results obtained by Emerson, foi' the tests which he 

 made of similarly occurring striped plants led him to the conclusion 

 that the striped individuals were merely heterozygous green plants in 

 which the green was not fully dominant. 



Emerson (10) mentioned that these yellowish-white plants some- 

 times become greenish, and one individual in the greenhouse lived to 

 the age of seven weeks. Perhaps the conditions out of doors were more 

 favourable for the development of these peculiar yellowish-white plants, 

 for during the season of 1912 several of them became fully green. The 

 position of some such jjlants was so well designated that there was no 

 mistake as to their identity, and two of the individuals were self- 

 pollinated. From the ears of the two plants 278 seedlings were grown 

 in the greenhouse, 277 of which were of the yellowish-white type, and 

 one was green. Undoubtedly the green plant was the result of an 

 accidental foreign pollination, for it is possible that a single pollen 

 grain from some green plant may have come in contact with one of 

 the silks. The fact that the yellowish-white plants breed true affords 

 additional evidence that a Mendelian recessive is being dealt with. 



From the study of the pure white plants and the yellowish-white 

 ones it seems that both are simple recessives, yet it appears that more 

 than one factor must be concerned. Believing that there were different 

 factors involved, crosses were made between gi-een plants from a f;imily 

 which had thrown pure white seedlings, and green plants from a family 

 in which yellowish-white plants had occurred. It was hoped thus to 

 secure crosses of heterozygous green plants which, if self-pollinated, 

 would throw 25 per cent, pure white seedlings, with heterozygous green 

 individuals which, if self-pollinated, would yield 25 per cent, yellowish- 

 white seedlings in the next generation. The green plants which were 

 crossed were also self-pollinated. In Table I are indicated only those 

 crosses in which both parents were shown to be heterozygous. 



It is interesting to note that the first generation of the cross between 

 the heterozygous green plants of the two categories consisted of 362 

 fully-green plants and one which was very faintly striped. From this 

 it appeal's that some factor which was lacking in one parent must have 

 been present in the other parent, in order that all the F^ plants should 

 be green. Otherwise it would be expected that in such a cross one- 

 foui'th of the F^ plants would not be fully green, owing to the fact that 

 the cross was between two heterozygous plants each of which, when 



