553 
Female Strobilus in Podocarpus. 
is completely lost sight of in the subsequent swelling of the bract bases. 
In section, however, the vascular strand is always traceable (Fig. 58, 
v. b., 3 br). 
As growth increases the bract bases begin to swell a little, but the 
lamina are still distinct (Figs. 56 and 58) ; by the pre-fertilization stage, 
however, their identity may be said to be entirely lost (Fig. 59). 
Histology. In longitudinal section of the pollination stage the ovuli- 
ferous scale has grown well above the bracts (Fig. 57, o.s .), and it shows a pro- 
duction of the apex above the insertion of the ovule. The vascular system of 
two bundles starts in this apex, each from a hypodermal group of tracheides. 
It spreads ring-like below the insertion of the ovule, but as far as the available 
material goes no laminal branching occurs (Figs. 57 and 58, v. b. 0. s). Resin 
canals with epithelium accompany the vascular supply on the ventral side, 
limiting the tissue of the integument , in which the nutritive cells are arranged 
in the normal zone (Fig. 59, tan . and st.c .). 
The hypodermal cells at the micropyle show spiral thickening and 
elongation (Fig. 57, a.). The nucellus is roundly pointed, but not beaked ; 
pollen-grains rest on the apex, but no tubes are traceable. Two or three 
layers of tapetal tissue limit the nucellus in the vicinity on the dividing 
macrospore (Fig. 57, tap). 
In an older stage (Fig. 58, pro) the ? prothallus shows free nuclei. 
In this case the tracheides of the vascular system of the third bract come 
into the section, though the presence of the former is not otherwise indicated 
(Fig. 58, v. b. } 3 brs). 
In older stages again, collected at Auckland in October, the bract 
bases were already swollen up to their mature size and identical in colour 
with that of the Yew aril, points alone indicating the laminae (Fig. 59, br. bs). 
The cells of the bract bases show an increase in size and number, but 
not in contents, being evidently filled with a watery cell-sap. They retain 
their foliar structure ; the proliferation of cells taking place in the mesophyll, 
the arrangement of the cell layers in this tissue is retained (PI. LI 1 1 , Fig. 79). 
The ovuliferous scale shows increase in length, and centripetal lignifica- 
tion of the cells of the integument, involving half its tissue, is in progress. 
A two-layered megaspore membrane surrounds the ? prothallus, which is 
very much contracted. Archegonia can be traced in the apex of the pro- 
thallus. Many of the cells show two nuclei, which would point to the 
maturation of the oosphere (see p. 530). This would agree with the 
development of the ovular tissues, and the contraction of the prothallus 
shows that endosperm formation has not yet been initiated. 
In this case we see that the swelling and coloration of the bract bases, 
which are turgid with a sweet cell-sap, are present long before maturity. 
This development can therefore be of no use to the plant in facilitating 
distribution by the agency of birds, as stated by Pilger ( 40 , p. 22). 
