100 MASS. EXPERIMENT STATION BULLETIN 185. 



Crosses of White Marrow with Golden Eyed Wax. — The progeny of this 

 cross are less complicated than others having White Marrow in the 

 parentage. The fii'st generation beans, being mottled, show both yellow 

 and red splashes. Those of the F2 generation, showing only yellow either 

 in solid color or motthng, either breed true or yield white beans in the 

 expected ratio. Among some three hundred plants the records show two 

 buff (B) seeded plants. These are probably accidental strangers, yet they 

 may be a definite class occurring in small numbers; if so, no explanation 

 of their occurrence can be presented. 



Crosses of White Marrow with Burpee Stringless. — Other crosses have 

 shown that Burpee Stringless has a constitution similar to Grolden Eyed 

 Wax, with the addition of the determiner F, making the bean coffee 

 brown. The beans of the Fj generation were of a yellow-olive mottled 

 color. In the next generation a variety of colors appeared among the 

 mottled beans, — coffee brown, yellow, olive, chocolate brown and red. 

 In later generations these differentiated clearly into the coffee brown of 

 Burpee Stringless, yellow (C), light red (D), buff (B) and white. Self- 

 colored coffee-brown seeds have given all brown, brown and yeUow, brown 

 and white, and mixed progeny including all three tj'pes. Light red, 

 light mottled seeds have bred true, and have yielded white seeded plants 

 in the usual proportion of 3:L 



Crosses of White Marrow with German Black Wax. — The results of this 

 cross are similar to the previous one with the addition of the epistatic 

 black (G). There is the same confusion of colors in the Fj generation, 

 but on further segregation they separate into black, coffee brown, yellow 

 and white. The light red also appears and apparently dark red (E) also, 

 though in small numbers. 



We have no case where a parent plant of this color has been bred. One 

 yellow seeded plant, being selfed, yielded yellow and white in a 3:1 pro- 

 portion, and one solid black of the F2 generation yielded a mixture of 

 black and coffee brown. 



Crosses of White Marrow with Red Valentine. — This cross differs from 

 those just considered in that Red Valentine belongs to the red series. 

 There are red, black or brown beans appearing, but yellow does appear in 

 many of the mottled beans. One plant of mostly sohd yellow beans pro- 

 duced a progeny of yellow and light red mottled beans, the former in 

 larger numbers. There is a tendency to produce the dark mottled bud 

 sports referred to on page 98. There are other complications in this cross, 

 some of which can be explained only on the supposition that the White 

 Marrow plant used as a parent was heterozygous in its nature. This 

 might well be, for so long as the factor P is absent the pigment modifiers 

 and determiners might be interchanged without the external appearance 

 being changed. 



