FIFTEEN- AND SIXTEEN-CHROMOSOME OENOTHERA MUTANTS 87 
possible (providing 8-chromosome gametes are formed by 0. Lamarc- 
kiana) that one or two of those derived from the reciprocal cross were 
products of 97 + cTS unions. Notwithstanding the fact that 85 
percent of the lata X Lamarckiana, and 83 percent of the Lamarckiana 
X lata, seeds failed to germinate in the time allowed them — approxi- 
mately the same percentage of failures in both cases — 15-chromosome 
forms appeared in considerable numbers among the offspring of the 
first cross, but were almost entirely absent from the second culture. 
However, we do not know what the percentages of 14- and 15-chro- 
mosome offspring would have been had all the seeds of each cross 
germinated. 
Bearing in mind that we do not know "what may be the changes 
of front when exact data become available," it may be said that the 
C.S.H. cultures of mutant 0. Lamarckiana lata selfed and crossed both 
ways with 0. Lamarckiana confirm, in the main, the earlier statements 
by de Vries and Bartlett and point to the following conclusions re- 
garding this mutant: (a) Lata characters are transmitted through a 
portion of the egg cells, and not, except possibly in rare instances, 
through the pollen of this form, {h) 8- and 7-chromosome female gam- 
etes, capable of functioning, but as a rule, only 7-chromosome male 
gametes, capable of functioning, are produced by 0. lataP The 
majority of the 8-chromosome female gametes (probably not all) are 
bearers of lata characters, while the majority of the male and female 
7-chromosome gametes (probably not all) are bearers of Lamarckiana 
characters, (c) It now appears that when offspring result from 8+7 
and 7+7 unions, the majority of the former have lata, or /a/a-like 
characters, and the majority of the latter Lamarckiana characters, 
but, as in the case of 0. Lamarckiana, selfed, it is not safe to assume 
that such are the invariable results, since it is probable that at least 
a portion of the 15- and 14-chromosome offspring derived from 0. lata 
selfed, 0. Lamarckiana, selfed, and 0. lata X 0. Lamarckiana which 
cannot be classified as 0. lata and 0. Lamarckiana, are products of 
8+7 and 7+7 unions, respectively. As in the case of 0. La- 
marckiana, 0. albida is one of the common mutant offspring of 0. lata, 
selfed, and of 0. lata X 0. Lamarckiana and it seems quite probable 
that this form results from 8+7 unions. 
2^ Fourteen- and fifteen-chromosome mutants, particularly the latter, are found 
in practically all fair-sized cultures of O. lata X 0. Lamarckiana. No statement can 
be made concerning the appearance of these forms in cultures of the reciprocal cross, 
since only one has been reported thus far. 
