FIFTEEN- AND SIXTEEN-CHROMOSOME OENOTHERA MUTANTS 7 1 
to have combined the characters of 0. lata with the smooth, shining 
leaves of 0. Leata. (2) 0. elliptica, a Lamarckiana mutant. 
Of the II distinct types known to have 15 chromosomes, (i) 0. lata, 
(2) 0. albida, (5) 0. nanella lata and (6) 0. subovata are well-known 
forms, originally described by de Vries; (4) type 5509 was mentioned 
in an early note (Lutz, '08) ; (7) type 2256, as previously pointed out, 
was erroneously identified in 1908 as 0. nanella. All of the remaining 
five forms are new. The somatic chromosome numbers of 0. lata, 
0. albida, types 5509 and 2256 were reported in early notes by Lutz; 
those of 0. bipartita, 0. nanella lata, O. exilis, 0. subovata, 0. exundans, 
types 4499 and 5365 were communicated in the preliminary note to 
this paper (Lutz, 'i6a). 
A mutant of the Lamarckiana group is distinguished from the 
parental form and other mutants, not so much by some particular 
character — for few characters are peculiar to any one type alone- — as by 
the combination of characters which is peculiar to itself. Thus, 
0, lata has broad, heavily crinkled leaves, irregularly shaped buds 
(particularly true of the early buds), light yellow flowers with crumpled 
petals, barren anthers, etc. No one of these characters is peculiar to 
0. lata alone. The cleft petals and large percentage of flowers having 
4+ -rayed stigmas are striking characters of 0. bipartita, yet neither 
is peculiar to this form alone; it is the combination of characters pre- 
viously enumerated which distinguishes it from all other forms. A 
very striking illustration of this point may be found in the previously 
mentioned 15-chromosome mutant reported by Gates Ci5a, pp. 
147-148), namely, 0. incurvata. His illustrations and descriptions of 
this form clearly show that it is not entitled to be regarded as a lata- 
like form, for, although he states that it agrees with 0. lata "in the 
obtuse tips and deep crinkling of the leaves," he also says that it 
differs from 0. lata "(i) in the much narrower leaves with long 
petioles, (2) in having one edge of the leaf characteristically folded 
over, (3) in being as tall as Lamarckiana with long internodes, (4) 
in having more squarish buds which produce pollen." If, in con- 
nection with these statements, one compares his photographs of 
0. incurvata (Figs. 56 and 57) with that of 0. lata (Fig. 37), all in the 
rosette stage, one will see that 0. lata and 0. incurvata are about as 
unlike as any two mutants which may be mentioned. It is quite 
clear that the "obtuse tips and deep crinkling of the leaves" do not 
entitle this form to be regarded as /ato-like, since it is wholly unlike 
