35^ 



The Journal o\ Heredity 



ENLARGED SECTIONAL VIEW OF 

 FUNIFOLIA LEAF 

 One of the (har.ut eristic fc-atures of tlie 

 funifolia mutant is tlu- ru>;o.sity of the ventral 

 (convex) surface. This is clearly brouj;ht out 

 in the above drawinji, which was made by J. 

 Marion Shull from a mounted specimen. (Fig. 

 11.) 



iind tlie Jornwsu factor in praliuioUi 

 occupy identical loci, it \vill kiui the 



strongest possible support to the view 

 to which 1 have been led by other 

 considerations, that there is a wide- 

 spread homology of genotypic constitu- 

 tion in the Oenotheras. The necessary 

 crosses have been made to test this 

 question. 



Oenothera Lamarckiana mut. 

 mut. nov. 



pervirens 



AX ALL-GREEX, RECESSIVE MUTANT 

 FACILITATING ANALYSIS OF PIGMENTA- 

 TION FACTORS 



Oenothera Lamarckiana, as is well 

 known, is characterised by pink-coned 

 l)uds and greenish stems bearing nu- 

 merous papillate hairs, of which the 

 papillae are strongly reddened with 

 anthocyanin pigment. There are, in 

 addition, numerous characteristic de- 

 tails of form and size of all its parts. 

 Breeding experiments have shown that 

 Oe. Lamarckiana is a permanent heter- 

 ozygote in regard to certain factors 

 carried in one of its chromosome 

 pairs (chromosome I), and that in 

 one member of this pair (la or "vel- 

 ans^") there is a factor for red bud- 

 cones which is only partially dominant 

 to the recessive factor for green or 

 greenish bud-cones which occupies the 

 corresponding locus in the other mem- 

 ber, lb ("gaudens"')- It is probably 

 the lack of complete dominance of the 

 red-cone factor K<^, which gives Oe. 

 Lamarckiana its characteristic pink 

 cones. The presence of the recessive 

 green-cone factor r'^ is easily demon- 

 strated by crosses between Oe. Lamarck- 

 iana and species characterized by 

 green bud -cones, as this represents the 

 back-cross of a heterozygote to the 

 corresponding recessive and results in 

 a 1 : 1 ratio, except as the ratio may be 

 modified by linkage with lethal factors 

 or by selecti\e elimination. The pres- 

 ence of this receisves green-cone factor 

 (r) is also evidenced by the frequency 

 with which mutant derivati\es of 

 Lamarckiana ha\e green or greenish 

 buds. In most ca.scs these green- 

 Imddc-d mutants (liiTcr from Lamarcki- 



' Names l)y which O. Kenner has distinguished the two hereditary constitutions possessed 

 by different germ-cells in Oe. Lamarfkiana. They may be retained as names of the two members 

 of chromosome pair No. I in this species. 



