FIFTEEN- AND SIXTEEN-CHROMOSOME OENOTHERA MUTANTS 89 
series running to Lamar ckiana'' have either 14 or 15 chromo- 
somes.^^ 
0. stenomeres mut. lasiopetala, as Bartlett Ci5<2) has pointed out, 
resembles 0. Lamarckiana mut. lata in its behavior, with, of course, 
this exception: the 14-chromosome offspring of the former bear the 
characters of 0. stenomeres, and not of O. Lamarckiana. In each case, 
however, the offspring bear the characters of the 14-chromosome form 
which produced their mutant parent. Furthermore, as in the case of 
0. lata, SL portion of the offspring (presumably having 15 chromosomes) 
reproduce the characters of the mutant parent. 
The behavior of 0, elliptica, if a 15-chromosome form, indicates 
that all of the gametes of one sex, capable of functioning, have 7 chro- 
mosomes, while the majority of those of the other sex which are 
capable of functioning have 7 chromosomes, and only a very few, 8. 
The behavior of 0. nanella lata indicates that only 7-chromosome 
female gametes are produced by this form since de Vries ('09, Vol. I., 
p. 374) found that 0. nanella lata X 0. nanella "gave rise to ordinary 
nanella only." From 0, lata X 0. Lamarckiana de Vries ('13, p. 257) 
obtained two dwarfs through mutation. " Der eine hatte nebenbei die 
Merkmale der Lamarckiana, der andere diejenigen der Lata. Beide 
hatten Pollen, und wurden damit rein befruchtet. . . . Die letztere 
gab zwar auch nur Zwerge . . . , spaltete sich aber in bezug auf die 
Lato-Merkmale in 9 La/a-Zwerge und 18 gewohnliche Zwerge, . . . 
The latter, upon self-fertilization, proved constant, but the lata 
dwarfs behaved in the same manner as the parent, when selfed.^'^ If 
this lata dwarf is the same form as de Vries's 0. nanella lata, then the 
available evidence indicates that all of the female cells of this mutant 
which are capable of functioning contain 7 chromosomes, while the 
majority of the male contain 7 and a smaller number 8.^^ Little or no 
consideration should be given to this evidence, however, since we do 
not know that the two mutants combining nanella-lata characters 
were duplicate types; furthermore, we have no assurance that a suf- 
ficient number of offspring of 0. nanella lata X 0. nanella were grown 
29 This condition was earlier indicated by Bartlett ( 15a, p. 103) in the statement 
that " Oe. scintillans acts like Oe. lata in every way." 
^° 0. ruhrinervis lata, which appeared in Schouten's 1906 culture of 0. rubrinervis 
(Schouten, '08), suggests a 15-chromosome condition, as Gates ('15) has stated, but 
since the chromosome number of this plant is unknown and that of the parental 
type unestablished, the behavior of this mutant will not be discussed at present. 
The behavior of O. ohlonga, if a 15-chromosome form, is somewhat contra- 
dictory and will not be discussed here. 
