VOLUME LXXIII NUMBER 4 
THE 
BOTANICAL GAZETTE 
April 1922 
DEVELOPMENTAL SELECTION IN VASCULAR PLANTS* 
Joun T. BUCHHOLZ 
(WITH TWENTY-EIGHT FIGURES) 
In the numerous explanations and discussions of natural 
selection in the Origin of species and since the time of Darwin, the 
process of competition has usually been regarded as taking place in 
the external environment. In striking contrast with this, devel- 
opmental selection is characterized by the fact that it occurs 
between very minute or embryonic individuals whose struggle is 
limited to what might be termed an internal environment. It is 
well illustrated by the selection resulting from the polyembryony 
within the developing seeds of conifers and cycads, the embryonic 
selection in this case being a special form of developmental selection. 
The embryos of the latter are wholly surrounded by organic tissue; 
they are entirely inclosed within the ovule of the parent plant. 
Equivalent forms of developmental selection are found in ferns as 
well as in angiosperms, and it is intended to discuss briefly these 
internal selective processes in their relation to organic evolution. 
Developmental selection is not to be confused with any of the 
older well known theories involving internal forms of selection. 
WEISMANN’s germinal selection is described as an internal process, 
but this is a supposed struggle between biophores within the germ 
cells; it is not even a competition between individual cells, and 
can be imagined only. It is based on a speculative hypothesis 
* Presented before the Botanical Society of America, Chicago, December 29, 1920. 
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