1922] BUCHHOLZ—VASCULAR PLANTS 251 
the external environment. That a selection may occur during the 
earliest developmental stages of an individual, for instance, during 
Fics. 1-6.—Embryos of Pinus Banksiana showing embryonic selection: fig. 1, 
two neighboring archegonia giving rise to embryos; fig. 2, system of eight embryos 
produced by fertilization of two neighboring archegonia, with sixteen embryos, eight 
primary embryos (below), and eight rosette embryos (above), participating in the 
n. 
competitio: 
the embryology or during the processes of seed development, is 
an idea that apparently has not been considered seriously by 
