

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-flowered plant with yellow stamens 

 which we have seen producing white-flowered progenies when 

 mated with red (families 10275 and 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 an d 10278 consisted of 43 pink-flowered 

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

 flowered plants and i 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) and 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 10301 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 



