No. 597] INHERITANCE STUDIES IN PISUM 



54 5 



yellow pigment, green may be regarded as epistatic to 

 yellow. 



The majority of varieties with yellow cotyledons 

 when crossed with varieties having green cotyledons, 

 have yellow cotyledon F 1 offspring, the F 2 generation 

 breaking np into yellow and green cotyledon plants in the 

 ratio of 3Y:1G. 



The yellow cotyledon variety "Goldkonig" when 

 crossed with green cotyledon varieties has green coty- 

 ledon F 1 offspring, in F 2 giving a ratio of approximately 

 1Y:3G-, just the reverse of the ordinary result. 



"Goldkonig" crossed with other varieties having yel- 

 low cotyledons has yellow cotyledon F 1 offspring, in F 2 

 giving a ratio of approximately 13 yellow seeds : 3 green 

 seeds. 



With these facts in view, ' 'dominant yellows'' may be 

 represented by the formula YYG-GTI, ' ' recessive yellows ' ' 

 (G-oldkonig) by the formula YYggii, and green cotyledon 

 forms by the formula YYGGii. These formulae account 

 for all the facts so far discovered in experiments on the 

 inheritance of cotyledon color in Pisum, except the data 

 "ii linkage or coupling, referred to in page 539, note 7. 

 These results will be discussed when more data are 

 available. 



LITERATURE CITED 



1. Bateson, W v and E. R. Saunders, and others. 



1902-1906. Reports to the Evolution Committee of the Royal So- 



2. Bateson, W. ^ 



1909. Mendel's Principles of Heredity. Cambridge (Eng.), Uni- 

 versity Press, pp. ix -f 396. Fig. 37. PI. VI. 



3. Baur, E. 



1911. Einfiihrung in die experimented Vererbungslehre. G. Born- 

 triiger, Berlin. S. 293, Fig. 80. Tafn. 9. 



4. Castle, W. E. 



1912. The Inconstancy of Unit-characters. Amer. Nat., 46, pp. 352- 

 362. 



5. Collins, G. N., and Kempton, J. BT. 



1911. Inheritance of Waxy Endosperm in Hybrids of Chinese 

 Maize. IV Conf. Internat. de Genetique, pp. 547-557. 



6. Correns, C. 



1900. Gregor Mendel's Regel iiber das Verhalten der Nachkom- 

 menschaft der Rassenbastarde. Ber. d. d. Bot. Gesell. 18, S. 



