74 



MASS. EXPERIMENT STATION BULLETIN 185. 



The results secured in the work here reported can be quite satisfactorily 

 explained on the above theory. All crosses of mottled beans have yielded 

 only mottled beans, as shown on pages 67 and 68. 



Some crosses of self-colored beans have yielded mottled progeny. 

 (See Table IV.) In most such crosses Blue Pod Butter is one of the 

 parents. If it has the constitution PYz then the other members of the 

 crosses must be PyZ. Self-colored beans of either of the above types, 

 when crossed with mottled beans, have yielded mottled and self-colored 

 beans in the proportion of approximately 3:1, as shown in Table II. 



The mottling factors of white beans are not so readily determined, 

 and there seems to have been more than one strain of some of the white 

 varieties used. Davis Wax seems always to carry the coupled factors 

 YZ. (See Tables III. and V.) It is probable that there are three strains 

 of White Marrow, as follows : — 



Crosses involving Creasehack. — In crosses involving Creaseback the 

 beans in F] have always been black or nearlj^ so. In the cross with Chal- 

 lenge Black Wax the beans were nearly black, but with faint signs of 



