130 BOTANICAL GAZETTE [AUGUST 



were those in which the wild poppy was crossed with its garden 

 derivatives, for as already noted the margin is a new character 

 which does not normally occur in the wild poppy. In the two 

 families representing such matings, the wild poppy was used as 

 the mother in 10298 and as the father in 10310. Both families 

 consisted of mixtures of margined and unmargined plants, showing 

 conclusively here also that margined petals is a dominant character, 

 since the wild plants are certainly homozygous in the lack of such 

 margins. The dominance of the margined condition of the garden 

 poppies over the unmargined condition of their wild prototype is 

 in marked contrast to all the other color-characters of Papaver 

 Rhoeas yet investigated, for the dark red-orange body-color 7 of 

 the wild poppy is epistatic to all the body-colors presented by 

 the numerous garden forms. If dominance were a secure criterion 

 of the presence of a gene which is absent in the recessive type, 

 these results would indicate that while the various body-colors 

 of the garden forms originated as retrogressive mutations, i.e., 

 by losses of characters, the white margins of the petals represent 

 a progressive mutation through the addition of a gene which 

 inhibits the development of color in that region. Doubleness 

 also proves to be dominant over the single type of the wild poppy, 

 and, on the basis of the same assumption, would have to be classed 

 as a progressive mutation. I cannot forbear, however, to repeat 

 the caution that dominance does not necessarily demonstrate the 

 progressiveness of a mutation, since the alternative hypothesis, 

 mentioned above in the first paragraph, allows for the dominance 

 of a character which has originated by a retrogressive mutation. 



There is still one other color-inhibitor (possibly several) in 

 the derivatives of Papaver Rhoeas, which is in some respects more 

 noteworthy than that which produces the white margins. This 

 affects the body-color of the petals, producing what is essentially 

 a dominant white, though in this case the inhibition is not usually 

 complete and the flowers often show some irregular striation of 

 dull violet, reddish, or bluish color on the petals, especially in 

 the presence of purple stamens. 



By the expression "body-color" it is intended to indicate the color of the general 

 intermediate region of the petals as distinct from "center" (proximal) and "margin" 

 (distal). 



