544 THE AMEBIC AX X AT ERA LI ST [Vol. L 



acter of the F 3 progeny, providing this interpretation of 

 the facts regarding cotyledon color in Pisnm holds, is 

 also indicated in this table. 



Additional data on the inheritance of cotyledon color 

 in Pisum will be given in a succeeding paper. 



Conclusions and Summaby 

 Variation in cotyledon color in Pisum belongs to all 

 three of the categories of variation mentioned in the fore- 

 part of this paper, although there are no definite data as 

 regards the origin of the green cotyledon and the "re- 

 cessive" yellow cotyledon varieties. 



1. Variations in cotyledon color due to environment 



(a) Yellow cotyledon varieties producing seeds with 

 green cotyledons, because of immaturity, absence of suf- 

 ficient sunlight, excess moisture at the period of ripening 

 of the seed, etc. 



(b) Green cotyledon varieties, especially those with 

 wrinkled seeds, producing seeds which fade or bleach to 

 yellow or yellowish green owing to excess of moisture and 

 sunlight after the seed has matured. 



2. Variations due to innate or hereditary differences 

 probably arising as mutations are: 



(a) Different degrees or intensities of yellow and green 

 coloring in the different varieties of Pisum. These differ- 

 ent intensities are characteristic of particular varieties 

 when all varieties under consideration are grown under 

 approximately the same environment. 



3. Hereditary distinctions as regards cotyledon color 

 in Pisum may be represented by the presence and absence 

 of two factors, a factor (I) causing green pigment to 

 fade when the variety matures its seed, and a factor (Gr) 

 causing the production of green pigment. All varieties 

 of Pisum so far experimented with, have yellow pigment 

 in their cotyledons and the determiner or determiners re- 

 sponsible for this pigment may be graphically repre- 

 sented by (Y). As the presence of green pigment masks 



