1gto] SAXTON—WIDDRINGTONIA 45 
As stated in the introduction, it is not proposed to discuss the facts 
here reported until the corresponding facts in the life history of 
Callitris are published, when the two genera may conveniently be 
compared and contrasted. 
Summary 
The microsporophylls are arranged in decussate pairs and each 
bears four microsporangia. 
The mature pollen grain is uninucleate. 
The four equal megasporophylls are opposite and decussate. 
About 64 megaspore mother cells are organized at the base of the 
nucellus, but only one is functional. Peculiar structures are noted 
at the poles of the non-functional megaspore mother cell. 
The megaspore may show polarity before the first division of the 
nucleus, or when four nuclei are present. The divisions of the embryo 
sac nuclei are probably simultaneous. ; 
Cell formation in the prothallus is normal in most respects, but 
certain peculiarities have been noted in the nuclear divisions which 
suggest comparison with Cryptomeria. 
The archegonia are never situated at the apex of the prothallus, 
but in several groups organized in relation to the pollen tube and 
deep-seated in the prothallus. The lowest group abuts on the pollen 
tube; the upper groups do not, and may possibly represent archego- 
nium initials. In the lowest group four neck cells are formed and a 
ventral canal nucleus is cut off. The total number of archegonia 
in a prothallus varies from about 30 to about roo. 
The microspore nucleus remains undivided for a long time. In 
other respects the development of the male gametophyte is more or 
less normal, but the so-called “stalk” and “tube” nuclei are almost 
invariably exactly alike and tend to disappear completely in the ma- 
ture pollen tube. 
The proembryo completely fills the archegonium, but the arrange- 
ment of the cells is somewhat variable. Walls are formed when less 
than eight free nuclei are present. 
The mature embryo has two (very rarely three) cotyledons. 
The cells of the mature prothallus are all binucleate or multinu- 
cleate. 
