216 



Inheritance in Ricinus communis, L. 



mahogany into rose. This factor can perhaps be regarded as a colour 

 inhibitor. 



M. The factor for mahogany. 



Relation between the factors S (spines), and M (mahogany). 



The cross green, bloom, spineless by mahogany, no bloom, spiny, is 

 of the nature GB sm x gb SM. 



Owing to the difficulty of separating rose (MG), from tinged (mg), in 

 F2, it was not possible to study the relation of S and M in F^ families 

 of this cross. 



From the results of the back-cross of F^ by double recessive sm 

 (green spineless), placed below, it will be seen that the four phenotypes 

 SM, Sm, sM, and sm occur in the ratio 1:1:1:1. 



Back-crosses of Sm Sm x smsm. 



Conclusion. 



The factors S and M are independently inherited. 

 Relation between the factors B (bloom) and S (spines). 

 The relation between these two factors has been studied in a cross 

 between Bs and bS. The F^. results of this cross are given below. 



Family 



BS 



