542 THE AMERICAN NATURALIST [Vol.L 



ledons of their mature seeds. The crosses of dominant 

 yellow with Goldkonig were: 



"Pisum Jomardi" X Goldkonig 

 Goldkonig X ' ' Mummy Pea 1 ' 

 Goldkonig X Wachs Schwert 

 "Pisum el at ius" X Goldkonig 

 First of All X Goldkonig 

 Gold von Blocksberg X Goldkonig 

 Spate Gold X Goldkonig 

 Benton X Goldkonig 



All the yellows other than Goldkonig yellow gave the 

 ordinary Mendelian ratios when crossed with varieties 

 having green cotyledons. No greens were obtained from 

 crosses between varieties having yellow cotyledons, other 

 than those with Goldkonig. 



Theoretical Interpretation 

 Interpreted in Mendelian terms the above data are 

 brought into accord with other data on the inheritance of 

 cotyledon color in Pisum by regarding all varieties of 

 peas, both with yellow and with green cotyledons, as pos- 

 sessing a factor for yellow pigment (Y), while the domi- 

 nant yellow varieties possess a factor for green pigment 

 (G) and a factor (I) which causes the green pigment to 

 fade on the maturity of the seed. The German variety 

 "Goldkonig" may be regarded as lacking both the factor 

 for causing green pigment and the factor for causing that 

 pigment to fade on the maturity of the seed, while the 

 green varieties lack only the factor (I). Green pigment 

 masks yellow pigment, hence may be regarded as epi- 

 static to yellow pigment. 

 Regarded thus: 



(1) YYGGII = dominant yellow varieties 



(2) YYggii = recessive yellow varieties 



(3) YYGGii = green varieties 



