ANNE M. LUTZ 
ate. While they did not tell us whether this occurs more frequently in 
terminal than in basal buds, it is probable, judging from the evidence 
produced by the 21-chromosome hybrids mentioned, that the extra 
chromosomes of i4+-chromosome forms degenerate more frequently 
in the buds produced near the end of the stem or branch than in earlier 
ones; or more frequently in the buds of a short, weak lateral or sub- 
lateral produced near the close of the flowering period of the plant, 
than in the buds of a vigorous branch. 
Since 15-chromosome forms commonly produce no pollen or very 
little seemingly good pollen, one can exercise but little choice in the 
selection of pollen-flowers; yet if it were possible to self one of the early 
flowers of the stem or a vigorous branch (not necessarily one of the 
first), he might secure a higher percentage of 15-chromosome offspring 
than is common, and even some i6-chromosome forms. Terminal 
flowers are avoided for obvious reasons; they are commonly regarded 
as less vigorous than earlier onfes, and those of annual plants are usually 
produced too late to ripen seeds; furthermore, even those of 14-chro- 
mosome forms frequently produce less pollen than earlier ones and 
such pollen as is produced often contains a low percentage of seemingly 
good grains. Terminal flowers of 15-chromosome forms or other 
(14 H — 28) -chromosome individuals producing but little pollen are 
usually entirely male-sterile; yet by covering the stigmas of early and 
late flowers of 0. lata with Lamarckiana pollen and employing some 
method which will secure the germination of all viable seeds, one should 
be able to ascertain whether the early flowers produce more 8-chro- 
mosome eggs, capable of functioning, than the late.^^ 
4^ In "New dimorphic mutants of the Oenotheras" referred to in note 36, de 
Vries has shown conclusively since the above was written that in the case of the indi- 
vidual 0. cana which he employed, at least, as high a percentage of offspring dupli- 
cating the characters of the mutant parent was produced by seeds derived from 
selfed terminal buds of the stem and side branch as from those of selfed basal buds 
of the same parts. If 0. cana has 15 chromosomes, as is probable, he has shown that 
the relative number of 8-chromosome female gametes was not less in the terminal, 
than in the basal, buds of the stem and a side branch of the plant employed. We 
may find this to be true of all 15-, or even of 14-}— chromorome forms in general, but 
we must not overlook the fact that the germ cells ot O. cana have not been studied 
as yet, and it may be that degeneration occurs less frequently in certain 14-I— chrom- 
osome types, or individuals of a given type, than in others. It may be, further- 
more, that chromosome degeneration is less likely to occur in plants having 15 than 
in those having 21 or 22 chromosomes. De Vries having found that a higher per- 
centage of the offspring of selfed biennial, than of selfed annual, 0. cana and 0. 
