LUTHER BURBANK 



we have already referred, was that certain quali- 

 ties of the pea are grouped into very conspicuous 

 pairs. 



His investigation led him to believe that there 

 are at least seven differentiating characters that 

 could be relied upon to reproduce themselves with 

 certainty in the offspring of the pea. These char- 

 acters, which he came to speak of as "unit" char- 

 acters, are the following: 



(1) The form of the ripe seed, which may be 

 roundish, either with or without shallow wrinkles, 

 or angular and deeply wrinkled. 



(2) The color of the reserve material in the 

 cotyledons or little leaves that first appear when 

 the seedling comes out of the ground; the colors 

 being pale yellow, bright yellow, orange, or green. 



(3) The color of the seed coats; white, as is 

 usual in peas with white flowers, or gray, gray- 

 brown, leather-brown, with or without violet 

 spots, etc. 



(4) The form of the ripe pods, whether inflated 

 or constricted or wrinkled. 



(5) The color of the unripe pods, whether light 

 or dark green or vividly yellow, these colors being 

 correlated with colors of stalk, leaf, vines, and 

 blossoms. 



(6) The position of the flowers, whether axil- 

 lary or terminal. 



[88] 



