548 WHITE— STUDIES OF INHERITANCE IN PISUM. 



Varieties Studied. 

 Irish Mummy of H. Eckford, Wem, England. This is the com- 

 mon fasciated variety, which in the seed catalogues of different 

 countries takes different names. In England fasciated varieties are 

 called crown peas. I have experimented with several other fasciated 

 varieties which were obtained from Russia and Sweden. 



Results from Crossing. 



Fasciated stems, umbellate inflorescence X non-fasciated stems, 

 axillary inflorescence gives in F^ absolutely " normal " stems with 

 axillary inflorescences. In Fo, Mendel obtained from 858 plants, 

 651 with normal stems and axillary inflorescences and 207 with 

 fasciated stem and umbellate inflorescences — a ratio of 3.14:1. 

 Lock (56) and others have confirmed Mendel's results, although 

 Lock notes there is considerable variation in the degree of fascia- 

 tion in the segregates. Bateson and Punnett (3) secured various 

 intermediate types in F„. 



Mendel carried his study of this cross through the F^ genera- 

 tion. In F,, of 100 " normal " F„ plants, 33 bred true to normal- 

 ness, while 67 gave both normal and fasciated plants in a 3 : i ratio. 

 In F^ no exceptional results were obtained. 



Interpretation. 



Considering only genetic results, the hereditary difference be- 

 tween " normal " stemmed and fasciated stemmed peas is the pres- 

 ence and absence of a single factor Fa. When Fa is present, the 

 stems are normal. In its absence, they are fasciated. 



8. Leaf Axil Color. 

 Generally associated with leaf axil color is color at the point of 

 attachment of the pinnae, colored margins in the young leaves and 

 color at the base of the stem. The color is either red associated with 

 pink flowers, or reddish purple associated with reddish purple 

 flowers. Owing to changes in environment, particularly the amount 

 of sunlight, the color varies in intensity even among the axils of the 

 same plant. Although always associated with colored flowers and 



