MENDELIAN INHERITANCE IN OENOTHERA PRATINCOLA 5 



the cross mut. formosa X f . typica C was unsuccessful. But the pollen of 

 mut. latifolia had been shown to be equivalent to the pollen of the f . typica 

 from which it arises (the mutation to latifolia being concerned with the 

 a gamete, the /? gamete remaining as in f. typica), and therefore, in order 

 to have a more complete series of crosses to work upon, the cross mut. 

 formosa X mut. latifolia from strain C was used in place of the missing 

 cross, mut. formosa X f . typica C. The substitution has been justified by 

 later work, recorded in tables 5 and 6 of the present paper, which give anal- 

 yses of the Fi and F 2 generations of the cross mut. formosa X f . typica C. 

 This cross was successfully made three years after the original crosses 

 upon which much of the work recorded here is based. 



The Fi generation (see table 5) consisted of 100 plants from six different 

 crosses, all of them flat-leaved. The F 2 generation (see table 6) consisted 

 of 3274 plants, 2399 flat-leaved and 875 revolute-leaved; that is, a ratio of 

 2.74:1, in sufficiently good accord with the 3:1 of the Mendelian mono- 

 hybrid ratio. The cross mut. formosa X mut. latifolia C, as recorded in 

 the previous paper, gave in the FI generation 209 plants, all of them flat- 

 leaved, and in the F 2 generation from normal f. typica plants of the FI 

 generation, 6392 plants, 4759 flat-leaved and 1633 revolute-leaved; that is, 

 a ratio of 2.91 : 1. This shows that the results in the F 2 generation are the 

 same whether mut. formosa is pollinated by f . typica C or by mut. latifolia 

 C ; and this, in connection with the previous evidence (CoBB and B ARTLETT 

 1919) of the equivalence of the pollen from the two sources, gives ample 

 justification for the substitution of f. typica M descended from mut. lati- 

 folia instead of the identical form descended from f. typica C. 



THE F 3 AND F 4 GENERATIONS OF THE CROSS MUT. FORMOSA FROM STRAIN E 

 X MUT. LATIFOLIA FROM STRAIN C 



The F 3 and F 4 generations of the cross mut. formosa X mut. latifolia C 

 show a continuance of the Mendelian behavior of the F 2 generation (COBB 

 and BARTLETT 1919). Self-pollination of normal f. typica plants of the F 2 

 generation gave in the F 3 generation (see table 2) 22 progenies consisting 

 entirely of flat-leaved plants, showing the presence of homozygous dom- 

 inants (a'(3FF) in the F 2 generation, and 41 progenies in which there were 

 both flat-leaved and revolute-leaved plants, showing the presence of 

 heterozygous dominants (a'pFf) in the F 2 generation. The ratio 22 uni- 

 form cultures to 41 segregating cultures very closely approximates the 

 expected ratio of 1 homozygous dominant to 2 heterozygous dominants 

 in the F 2 generation. In the segregating progenies of the F 3 generation 



GENETICS 6 : Ja 1921 



