276 BOTANICAL GAZETTE ’ [APRIL 
Interfloral selection is a form that may occur between the 
individual florets of a crowded inflorescence, such as the head of 
Compositae, the spike of maize, or the umbelled cluster of flowers 
in Asclepias. It is to be referred back to a struggle between the 
embryos contained in the different flowers, but since this competi- 
tion is indirect, it is not usually very decisive. The process is 
less secluded from environmental influences, and takes on a form 
somewhat similar to the selection between vegetative branches 
described later. Interfloral selection is of little consequence in 
evolution as a form of developmental selection, except probably in 
rare instances. 
VEGETATIVE FORMS OF DEVELOPMENTAL SELECTION.—Thus far 
the reproductional phases of developmental selection have been 
the chief concern. These reproductional types of selection are 
by far the most important, since through sexual reproduction new 
zygotes combining diverse hereditary strains come into existence. 
The developmental selection which takes place during reproduction, 
therefore, is a kind which may occur between different phenotypes, 
and produces results that are genetically very significant. 
That there are also vegetative forms of this developmental 
selection process should not be overlooked, but this vegetative 
selection remains within the same genotype, unless a vegetative 
mutation occurs. For example, the branches of a tree are in a state 
of competition for light and favorable exposure. A struggle for 
development was suggested long ago by Miter, who pointed out 
that there are many times more buds on every twig of a tree than 
can possibly develop into branches. While external circumstances 
of exposure may largely determine the result of this selection, the 
merits of the individual buds and their branches are also responsible 
in part for the result. If bud mutations occur, this vegetative 
selection determines at once whether they shall survive to reproduce 
themselves later or be eliminated. The principle is very largely 
the same for any form of vegetative selection, whether in gameto- 
phyte or sporophyte, by the dichotomy of thallus, aerial branches, 
stolons, tubers, rhizomes, or roots. When practiced for the pur- 
pose of obtaining vegetative mutation, bud selection has been 
called clonal selection. Of course, it is evident that this selection 
