Heredity Studies in the Morning-Glory 37 



The seed coat is either black or yellowish brown (tan). Black is the 

 dominant color. Black, being the dominant color in the maternal somatic 

 tissues, may lend character to the seed coat without giving any indication 

 whatever of the nature of the embryo within it. A black seed coat may 

 contain a homozygous or a heterozygous black embryo, or a homozygous 

 tan embryo. A tan seed coat may contain a heterozygous black embryo, 

 but never a homozygous black embryo. It may contain a homozygous 

 tan embryo. 



Feathering of the corolla is a mendelian character dominant over its 

 absence. 



The color of the corolla differed in the several types in the series here 

 studied. The types were progressively epistatic one to another from 

 white thru pink, magenta, and blue to dark purple. 



Anthocyanic colors are due to the action of enzymes upon colorless 

 chromogens, producing thereby colored pigments. 



The color types studied in the morning-glory were in complete accord 

 with the enzyme theory. Each epistatic type is due to the addition 

 of one or more genes probably enzymatic in nature which are not present 

 in the hypostatic type. 



Flaking is a dominant character in the morning-glory material here 

 studied. It is explained by a hypothesis supposing the character to 

 be due to an enzyme which is locally distributed in the corolla and which 

 reacts with a colorless chromogen to produce the colored flakes. Where 

 it is present without the gene for producing solid color, flaked whites 

 result; when present together with this gene, flaked solids are produced. 



153 



