132 
JOHN T. BUCHHOLZ 
PODOCARPINEAE 
The embryo development of the podocarps, according to the meager 
descriptions available, represents a condition much further removed from 
Pinus, one which is to be looked upon as modified from a form intermediate 
between Sciadopitys and the araucarians. In many respects, these podo- 
carp embryos illustrate some of the general tendencies of embryo modifica- 
tion which brought about the highly specialized araucarian type, and are 
therefore considered here. 
The proembryo of Podocarpus (fig. 17) consists of two very unequal 
tiers of cells, and some free nuclei in an open tier above. Figure 18 shows 
an early proembryo with suspensors elongating, and with its binucleate 
terminal cell undergoing further division in figure 19 before the embryo 
initials, which may separate, are formed. From the fact that these suspen- 
sor cells in this case were organized from free nuclei, one could infer that 
these are suspensor-forming embryo initials. The rosette cells of Pinus, 
which certainly are embryo initials, were sometimes found to elongate as 
suspensors (2), and we might expect to find some groups of conifers in which 
such unfavorably placed embryo initials are normally modified to form 
suspensors. 
While Podocarpus coriaceus (figs. 16-22), which was investigated by 
Coker (8), produced walls only after sixteen or more free nuclei were formed, 
Figs. 16-24. Stages in embryogeny of Podocarpus coriaceus, after Coker (8). Fig. 23. 
Podocarpus nivalis, showing binucleate terminal cell enclosed by a thick cellulose cap. 
Fig. 24. Embryos of P. ferrugineus. Apical cell stage appears to exist in figures 20 and 
216-24. Figures 23 and 24 after photomicrographs by Sinnott (39). 
