132 - BOTANICAL GAZETTE [august 



cross between a light-red and a striated individual produced three 

 offspring, all with flowers slightly darker red than those of their red- 

 flowered parent. Considering the complexity of some of these 

 families, this number of individuals is entirely inadequate for 

 the deduction that family 10268 was really exceptional. 



While I have laid no emphasis thus far on the fact, it may have 

 been noted that all of these poppy-families in which a "dominant 

 white" has made its appearance have been derived from red or 

 striated parents, never from red-orange or pink (light violet-red). 

 It seems that the factor under discussion is not a general inhibitor 

 of color but only of pure spectrum-red. The following facts seem 

 to prove this: The same white-flow r ered plant with yellow stamens 

 which we have seen producing white-flowered progenies when 

 mated with red (families 10275 an d 10281) was also mated with 

 two homozygous pink-flowered plants (families 10277 and 10278) 

 and a homozygous red-orange plant (10279) and in all of these 

 three crosses the white-flowered parent proved to be a recessive 

 white. Families 10277 and 10278 consisted of 43 pink-flowered 

 and 25 red-flowered plants, and 10279 contained 226 red-orange- 

 flowered plants and 1 red-flowered. Not a single individual in 

 any of these three families had white or whitish flowers. In 

 keeping with these results are families in which striated plants 

 were mated with pink (10295) an d red-orange (10301), for in 

 neither of these families appeared a white-flowered offspring or 

 one with striations, 10295 yielding 37 pink-flowered and 33 red- 

 flowered and 1 030 1 giving 22 which were red-orange and 5 inter- 

 mediate between this and red. 



The occurrence of many red-flowered plants in these families, 

 when one of the parents supposedly contained an inhibitor for 

 red, is not satisfactorily explainable on the assumption made 

 above, that there is a single inhibitor for red whose effectiveness 

 fluctuates to such an extent that its presence may not be detected 

 in its extreme minus-fluctuations. An alternative hypothesis may 

 be suggested, which must await further experimentation for its 

 confirmation or rejection. If there be two factors, A and B, 

 which are ineffective when existing apart from each other, but 

 which become an inhibitor when acting together, the observed 



