98 



ShuU. 



the capsules, I assumed the existence of two indepemlent factors, C and 

 D, the presence of either resulting in the development of the triangular 

 type of capsule characteristic ol B. hursa-pastoris (Shull 1911). Owing 

 to a rather large fluctuation in the ratios, the truth of my assumption 

 lacked adequate proof, and it remained at the close of the F3 merely 

 an interpretation having a certain degree of probability, like a number 

 of similar assumptions made by otiicr investigators. Complete demon- 



Fiy. '■ Cnjisuli's of liiirsa bursa-j/astofls (obovcl and of B. Hecgeri. 



stration of the duplicate genes, C and I), has now been supplied by 

 tlic results (if ail ample Fi, as will be seen in the tables given l)elow 

 and in the grajjliii' sunnnary presented in Fig. 5. 



Tiie superficial differences between the capsules of B. hnrsn-pasior/s 

 and of B. Heeyeri are now familiar to most students, but may be re- 

 called more easily by a reference to Fig. 1. The former have a strongly 

 flattened, triangular or obcoi'date form due to a simr-Iike inflation 



