416 BOTANICAL GAZETTE [DECEMBER 
develop up to the cotyledon stage even in cones from which 
most of the sporophylls have been removed in securing material. 
In cones which arrive in Chicago with embryos in early cotyledon 
stages, the development is completed perfectly and the seeds will 
germinate. 
Fertilization 
The relations of the various structures at the time of fertiliza- 
tion are shown in fig. 1. The outer fleshy coat of the ovule has 
become highly differentiated, with its epidermal and hypodermal 
layers and deeper tissues containing tannin cells, mucilage ducts, 
and the outer vascular system. The stony coat has become so 
hard that it is difficult to cut it with a strong pocket knife; in 
fact, material of this and later stages was secured by sawing the 
ovule transversely with a fine saw. The inner fleshy coat has 
been reduced to a thin, papery membrane which, in the figure, 
appears as a dark border lining the inner surface of the stony layer. 
The nucellus, with its conspicuous beak and pollen tubes, has 
begun to sag. The tissue of the female gametophyte has become 
quite firm and contains numerous tannin cells, while the arche- 
gonial chamber has reached its maximum depth, and the nucleus 
of the central cell of the archegonium has just divided to form the 
ventral canal and egg nuclei. As stated in the paper on spermato- 
genesis in Dioon edule (8), the archegonial chamber is moist but . 
contains no liquid before the pollen tubes begin to discharge. The 
sperms in escaping through the rather small rupture in the end of 
the pollen tube—there is no pit or pore—are much constricted, 
but soon regain their form and begin to swim. The amount of 
liquid discharged by a single pollen tube is small in comparison 
with the size of the archegonial chamber, and if the liquid should * 
spread evenly, it would not be sufficient to cover the sperms, 
however, it behaves somewhat like a drop of water on a greasy 
surface, not spreading much, but moving until it comes into con- 
tact with the neck of an archegonium. The sperms move vigor- 
ously after being discharged from the pollen tube, but how long 
they might continue to swim under natural conditions in the 
archegonial chamber could not be determined. I had little success 
in keeping them alive in sugar solutions. When a sperm comes — 
