Xo.5<)7] IMIKHITAXCE STUDIES IX PISUM 



531 



will deal with other characters and the modifications of 

 various characters through crossing. 



Of more than two hundred and fifty varieties and spe- 

 cies upon which the writer has been conducting experi- 

 ments, the great majority have seeds which in the mature 

 condition possess yellow cotyledons, but in such an array 

 of varieties, it was soon noticed that the shades of yellow 

 varied from a light greenish yellow to that of a deep 

 orange. Koughly one could divide these forms with yel- 

 low cotyledons into light and deep yellows, but any one 

 particularly "keen" on forming a series showing con- 

 tinuous variation, could easily grade the varieties so as 

 to present a series without breaks from light greenish 

 yellow to deep orange yellow. All the wild varieties and 

 species so far examined have yellow cotyledons, which 

 favors the assumption that yellow cotyledon is the oldest 

 color character. Many of the cultivated varieties and es- 

 pecially the so-called blue "field peas" such as Wisconsin 

 Blue and Prussian Blue and the majority of those known 

 as "garden peas" have green cotyledons when the seed 

 is mature. What has been stated regarding the grada- 

 tions of color in yellow cotyledon varieties is equally true 

 of those with green cotyledons. Koughly classified, there 

 are dark and light green forms, but the various varieties 

 can be arranged in a continuous series representing every 

 shade from very dark green to light yellowish green. 



Among the numerous green and yellow cotyledon varie- 

 ties, when grown under the same environment, there are, 

 however, many varieties to which certain distinct shades 

 of either green or yellow are peculiar. Some varieties 

 have characteristically deep orange cotyledons, others 

 have light yellow cotyledons, and still others breed true 

 to the shades between these two extremes. With the group 

 of green cotyledon varieties, the same state of affairs 

 holds true. Classification of yellows and greens is still 

 further complicated because some varieties with light yel- 

 low cotyledons grade into the light greens and vice versa, 

 even though both are grown under the same conditions. 



