FIFTEEN- AND SIXTEEN-CHROMOSOME OENOTHERA MUTANTS 75 
indirectly with that of its parents, for the results derived from the Cold 
Spring Harbor and Louvain studies indicate that 14-chromosome off- 
spring of i4+-chromosome forms may germinate as readily as 14- 
chromosome seeds of 14-chromosome forms. 
In the discussions of this report and others to follow, due allowance 
will be made for the facts above mentioned. With reference to the 
relative percentages of the various types of mutants appearing in de 
Vries's cultures, as quoted, these may not represent the actual per- 
centages as they would have appeared had all the viable seeds sown 
germinated, but they offer sufficiently satisfactory evidence to prove 
that many 15-chromosome offspring of 14-chromosome Lamar ckiana, 
alone, have neither lata, semilata, nor /a/a-like, characters; furthermore, 
it is probable that the majority of these 15-chromosome mutants, 
whether /a/a-like or not, are products of 7 -f 8 unions. However, if 
we believe that each 15-chromosome mutant is represented by a par- 
ticular chromosomal combination, then we will agree that an occa- 
sional 6 -f 9 union might produce the same combination as 7 -f 8 
and that the same type of mutant might result from the former as from 
the latter. This possibility may be illustrated very simply. 
Throughout this paper and in future reports, when we wish to 
indicate difference in sex without designating the particular sex of 
either gamete, we shall employ small capitals in italics to represent 
the chromosomes of a gamete of one sex and the same, marked ' , 
to indicate the chromosomes of a gamete of the opposite sex; thus, 
(cf or 9) Ascz>£FG + (cf or 9) a' b! d d' f! f' g' = aa' bb' cd 
dd' ee' ff' gg'. When it shall be necessary to indicate the sex of 
gametes, the chromosomes of the female will be designated by lower 
case letters in italics, and those of the male by the same, marked 
thus, 9 ah cdef g + a' h' c' d' e' f g' = aa' hh' cc' dd' ee' ff' gg'. 
Now, assuming that the regular female gamete of 0. Lamarckiana 
contains ab c d ef g chromosomes and the regular male a' b' c' d' e' f g' ; 
that the somatic cells of this form contain aa' bb' cc' dd' ee' ff' gg' 
chromosomes; then aab c d ef g + a' b' c' d' e' f g' might produce 
O. lata having aaa' bb' cc' dd' ee' ff' gg' chromosomes. So also might 
aa bb c d ef g + a'- c' d' e' f g' produce 0. lata having aaa' bb cc' dd' 
ee' ff' gg' chromosomes. While it is possible that a 6-chromosome cell 
is incapable of functioning in union with one having 7 chromosomes, 
or fewer, but is capable of functioning in union with one having 8 or 
8 -|- chromosomes, thereby producing a 14- or i4+-chromosome con- 
