H6 BOTANICAL GAZETTE [FEBRUARY 



sap-colors; while the yellow color of Matthiola and of Polemonium 

 flavum are plastid-colors and this must account for their different 

 behavior. In Mirabilis CoRRENS 4 has noted a yellow-flowered variety, 

 M. Jalapa gilva, in which the yellow color seems to be dominant. 

 I do not know that any examination has been made to determine the 

 basis of the yellow color in Mirabilis, but I predict that it will be found 

 to be a sap-color. HURST S reports, on the contrary, that the yellow of 

 Antirrhinum ma jus, which is recessive to white, is a sap-color. If 

 this statement is correct, this species seems to stand alone at present 

 in the possession of a sap-color recessive to white. Why a plastid- 

 color should be recessive to the absence of that color calls for an 

 explanation which science is not yet ready to give. This difference 

 between the two kinds of yellow recalls a similar situation in poultry, 

 in which white is usually dominant over colors, but in at least one 

 strain (Silky) the white is recessive. 



STATION FOR EXPERIMENTAL EVOLUTION 

 Cold Spring Harbor, L. I., N. Y. 



4 CORRENS, C., Zur Kenntnis der scheinbar neuen Mcrkmale der Bastarde. Ber. 

 Djutsch. Bot. Gesells. 23:70-85. 1905. 



s HURST, C. C., Mendelian characters in plants and animals. Rep. 3d Internal. 

 Conference on Genetics, 1906. Roy. Hort. Soc. 1907:114-128. figs. 6. 



