1919J HORTICULTURE. 537 



tiinn 40,000 plants. The data secured are presented in tabular form and cer- 

 tain hypotheses are advanced to accounl fur the facts observed. A bibll- 

 ography of cited literature is appended. 



This work shows, as in other Investigations, that the inheritance of seed 

 coat color in beans Is very complicated and difficult to explain fully and satis- 

 factorily. In a general way the crosses of pigmented and white beans show 

 a 3:1 ratio but there are certain wide departures. Certain correlations 00CUT 

 between seed and flower. All white or eyed beans are accompanied by white 

 flowers; all black or black mottled beans, by dark pink flowers. Mottle/1 beans 

 other than bho a mottled beans and those of various yellow and brown colors 

 are usually accompanied by light pink (lowers. 



The inheritance of mottling, it is BUggested, may be explained by the double 

 factor hypothesis of Emerson, 1 which theory supposes that mottling is brought 

 about by two factors, F and Z, which are coupled in the case of true-breeding 

 mottled varieties, but may be separately borne by distinct varieties, and in 

 such cases are Inherited Independently. Individuals from such crosses bearing 

 both V and Z are mottled and always heterozygous, while those bearing either 

 one are not mottled. Crosses Of two mottled varieties gave only mottled progeny. 

 Crosses of mottled and self-colored varieties yielded mottled beans in Fi and 

 the parent types in a 3: 1 ratio in F,. Crosses of mottled and white varieties 

 gave mottled beans in Fi and usually mottled, self-colored, and white in a 

 9:3:4 proportion In F 2 . 



"In most cases crosses of two self-colored varieties have given only self- 

 colored progeny. The principal exceptional variety is Blue Pod Butter, which, 

 when crossed with most self-colored varieties, yields mottled progeny none of 

 which breed true to the mottled character. White varieties may carry the 

 character for mottling, which can show itself only after crossing with a pig- 

 mented sort. Creasebaek is peculiar in that it seems to carry factors for 

 mottling and an additional factor causing a blackening which nearly or quite 

 obscures the mottled pattern. 



"There are two types of mottling — the dark, seen in Red Valentine and 

 Refugee and many others, and the light, seen In varieties of the Horticultural 

 class. The former behaves toward the latter as a simple dominant. Ap- 

 parently the factor for the dark mottling is associated with one of the mottling 

 factors. White beans may yield light mottled beans, but none have yielded 

 dark mottled beans. 



"There is evidently needed to produce a totally pigmented bean a factor for 

 total pigmentation. If it is absent when the factor for pigmentation is present 

 we have an eyed bean. Eye size is evidently governed by one or more factors, 

 but these Investigations do not afford definite data regarding their relations. 



"Pigment patterns and pigment colors are controlled by distinct factors. 

 According to the hypothesis presented in this paper, any color shown in a bean 

 seed is, in most cases, dependent on three or more factors. The basic factor for 

 pigmentation may be modified into either one of two series, one including the 

 various yellows, browns, and black : and the other, different shades of red. The 

 third factor, called a determiner, finally determines what the color is to be. 

 In some cases the determiners bring about the color through causing an alka- 

 line or acid condition. Possibly In some cases the color is determined by the 

 degree of acidity or alkalinity. 



"The two modifiers discovered are apparently associated with one of the 

 mottling factors, but the determiners are free and independent, though standing 

 often in an epistatic or hypostatic relation to one another." 



»Amer. Breeders' Assoc. [Proc], 5 (1909), pp. 368-37G. 



