96 MASS. EXPERIMENT STATION BULLETIN 185. 



of both the red and yellow-black series has bred true. From crosses 

 similar to the one just discussed we have extracted black mottled beans 

 similar to Refugee that have bred true, though not in large numbers. 



Mohawk has a seed coat color somewhat similar to Red Valentine and 

 Warwick, but the red color is darker and is changed to a bright red by- 

 acid solutions. It is assumed to carry the alkaline modifier E. When 

 crossed with Giant Stringless it yields in r2 numerous plants with coffee- 

 brown beans, indicating that Mohawk carries the determiner F. When 

 crossed with Burpee Stringless no yellow beans appear, for both these 

 varieties carry F, and the hypostatic yellow color cannot appear. 



Keeney Rustless crossed with Burpee Stringless yields many black beans. 

 This may be explained by assuming that Keeney Rustless carries the black 

 determiner G but not the modifier M, which prevents the appearance of 

 the black color. It does carry M' and E, and is therefore a dark red bean. 

 Burpee Stringless supplies the modifier M which with the determiner G 

 brings forth the black color. The cross Keeney Rustless X Burpee String- 

 less may be expressed by PmM'GfcED X PMm'gFC. It is probable that 

 Burpee Stringless carries an E also. Buff-colored beans appear in this 

 cross, indicating a lack of common determiners. 



Wardwell crossed with Giant Stringless and Burpee Stringless yields 

 progenies similar to those resulting from a cross of the latter two varieties 

 with Mohawk so far as pigments are concerned. Both Mohawk and 

 Wardwell carry the determiner F, but it is not expressed owing to the lack 

 of the modifier M. "When this is supplied by Giant Stringless or Burpee 

 Stringless coffee-brown flecks appear in the mottled beans, and various 

 types of mottled beans and both mottled and self-colored beans of the 

 yellow-black series may be isolated. 



Crosses involving CreasebacJc. 



In Table VI. were presented the manifestation of color patterns in 

 crosses of Creaseback with Blue Pod Butter and Challenge Black Wax. In 

 Table XXI. are shown the same crosses, giving the proportion of plants 

 exhibiting the various seed coat pigments involved. In the discussion of 

 Table VI. (page 74) it was brought out that Creaseback must carry the 

 determiner G, and its formula according to the hypotheses followed is 

 pyZMG. As soon as the factor for pigment is introduced by Blue Pod 

 Butter, which may be assumed to have here the formula PYzmG, black 

 beans appear making up all the Fj generation, and in F2 there follows what 

 is probably a 9 :3 :4 proportion with the buff of Blue Pod Butter and white. 

 The exact proportion is 9.21:2.55:4.31 when all lots sho-^ving the three 

 colors are combined. Where black seed parent plants show only buff or 

 white progeny besides black, and where buff seed parent plants yield 

 white seeded progeny, there is evidently a simple 3:1 proportion. 



In cross 97, Challenge Black Wax X Creaseback, there is evidently a 

 simple 3 : 1 proportion based on the presence or absence of the factor for 

 pigmentation. Cross 97 as tabulated is derived in part from a cross made 



