CYCAS RUMPHII. 
191 
the two shrivelled ones are in a state of decay. In this young 
stage the ovules are subglohose, but later on they become oval 
and somewhat elongated at the base (Fig. 3). The micropyle 
{mp.) is situated in a notch. The sporophylls form at first a 
cone-like dense cluster, but soon begin to spread out in a 
horizontal position. At this stage a drop of mucilage may be 
seen on the micropyle. The sticky mucilage collects pollen 
grains, particles of dust, spores of fungi that float in the air, 
are carried about by the wind, and happen to come into 
contact with the micropyle. Some time later the drop of 
mucilage, together with its load, is sucked in through the 
micropyle, which becomes hermetically closed, and ends in 
a pointed, dry, and sharp tip. 
In Fig. 2 is drawn a somewhat diagrammatic sketch of a 
pollen grain of Macrozamia as seen just before it is shed out 
of the poUen sac. It has already undergone partial germi- 
nation through a double nuclear division and wall partition. 
V. is the vegetative cell, often called the prothallus cell, g. the 
generative cell, t.c. the tube cell. 
Fig. 3 is a longitudinal section of a fully grown ovule of 
C. Rumphii. It is oval, but not quite regular in shape. Such 
an ovule is much larger than those of C. circinalis, and reaches 
some 6 or 7 cm. along its main axis. 
The integument is single, but consists of three distinctive 
layers : an outer fleshy layer a hard stony layer (st.l.), 
and an inner fleshy layer which is permeated by 
numerous vascular bundles not shown in the diagram. The 
inner fleshy layer is far from being uniform in thickness, 
being remarkably broad and spongy at the base of the ovule. 
This feature is characteristic of C. Rum'phii, as contrasted 
with C. circinalis. In the latter the inner fleshy layer is of 
a more or less uniform thickness, allowing the endosperm to 
expand freely into the shape of an egg, while the endosperm 
(end.) of C. Rumphii remains spherical, but somewhat flattened 
at the base. In this respect Fig, 127 in Coulter and Chamber- 
lain (after Miss Stopes) is misleading (1). The diagram does 
not represent a section of C. circinalis, neither as a young 
stage nor as a nearly mature seed, but agrees well with a 
grown-up ovule of C. Rumphii, as may be seen by referring 
