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THE AMERICAN NATURALIST [Vol. XLIV 



characters, which I have called 0. rubricalyx. None of 

 the peculiar characters of either parent are present in 

 this hybrid. But this is not so remarkable, because 

 crosses between the (Euothera mutants frequently lose 

 the distinctive marks of both parents and give 0. La- 

 mar<l-i(n/a. The same form, 0. nthrivuhjr, lias appeared 

 in my cultures as a mutant or extreme variant from 0. 

 rubrinervis, from which it differs only in possessing a 

 red hypanthium instead of green, a marked increase in 

 the red color pattern of the sepals (the median ridge of 

 the sepals being also red instead of green), and in the 

 production of a conspicuous quantity of red pigment on 

 the under surface of the petioles of the rosette leaves, as 

 well as in other parts of the plant. The type can there- 

 fore easily be recognized by observing the under surface 

 of the rosettes, and in the flowering stage the conspicuous 

 deep red buds render the plant very attractive and showy, 

 distinguishable from 0. rubrinervis at a glance. It dif- 

 fers from 0. rubrinervis in its greatly increased capacity 

 for anthocyanin production, a difference which expresses 

 itself in nearly every organ of the plant. A full illus- 

 trated account of this cross will be published elsewhere. 



In the F 2 this type splits in the Mendel ian ratio of 

 3 : 1, giving approximately 75 per cent. 0. rubricalyx and 

 25 per cent. 0. rubrinervis. I have not yet bred the 

 later generations, but the 0. rubrinervis may be expected 

 to breed true and the 0. rubricalyx to split as before. 



In this single cross there are many facts which throw 

 interesting side lights on the nature of Mendelian be- 

 havior. In the first place, only one character splits in 

 Mendelian fashion, the others remaining true. Hence, 

 if proof of this proposition were needed, here we have 

 proof that Mendelian phenomena are not universal, even 

 in the forms in which they occur. The O. rubricalyx 

 which appeared as a mutant from 0. rubrinervis also 

 splits in the same manner, a certain number of the off- 

 spring reverting to the rubrinervis condition, though I 

 have not been able to determine whether this is a Men- 

 delian ratio. These and other facts make it very prob- 



