sae CHAMBERLAIN—OVULE OF DIOON 329 
and edges but upon the entire upper half of the inner face. This 
gives the whole cone a brown color and a densely hairy appearance. 
It would seem impossible for the cone to be wetted by rains. The 
changes in temperature in this region are so slight that the hairy 
condition could hardly be related to this factor. 
The lower greenish sporophylls never bear ovules or even primordia 
ofthem. The next sporophylls have occasional primordia, but it 
is only when the larger sporophylls are reached that normal ovules 
ses 4-—Ovulate sporo- Fic. 5.—Ovulate sporo- Fic. 6.—Ovulate sporophyll, 
Phyl, back and side view. phyll, inside view; ovules abaxial side; one ovule with 
= essile. X 4. pseudo-stalk, the other sessile. 
x}. 
appear. Even the uppermost sporophylls bear ovules which some- 
times ripen into seeds. The uppermost sporophyll is almost circu- 
lar in transverse section. Its two ovules usually abort, as do those 
of the next sporophyll below it, but from this point, down to the 
sterile sporophylls at the base of the cone, each sporophyll bears two 
ovules which may develop into seeds. The ovules in a cone number 
about 100-300, and probably 200 ripe seeds is a liberal estimate for 
the larger cones. Where plants are isolated and pollination is uncer- 
tain, there are few ripe seeds, or even none at all. It would not be 
Sale to say that the ovules of Dioon do not attain their full size unless 
Pollination has taken place, for it is well known that the ovules of 
