16 BOTANICAL GAZETTE [JULY 
present in the Pteropsida. Still it remains true that they are not 
known actually to have done so. 
There are no microsporangiate structures known among lycopods 
that are at all comparable with the pollen cones of the gymno- 
sperms. Notwithstanding the puzzling diversity within the group, 
‘ it is still far easier to derive them from filicinean ancestors than from 
club mosses. In the latter the sporangia are uniformly single and 
adaxial instead of multiple and abaxial, as they are in ferns and 
gymnosperms. . 
With the exception of the Gnetales, the female gametophyte 
of the gymnosperms is so uniform in mature structure and in de- 
velopment as almost of itself to preclude any question of its diverse 
origin. The deep-seated megaspore, the vacuolated free nucleate 
embryo sac, the centripetal growth of walled tissue, the origin and 
development of remarkably uniform archegonia are common to 
all known members of the group, and form a unique and character- 
istic series unknown outside of it. 
The development and mature form of the embryo, with its 
free nuclear phase, organization into a walled proembryo, elongating 
suspensors, and terminal embryo, are no less striking and equally 
without analogy outside the group. Nor is there any sufficient 
diversity in the mature structure or in the course of development 
of the male gametophytes to cast serious suspicion on their common 
origin. The differences are strictly of degree, and find a ready 
explanation in the changes incident to a long course of evolution. 
As a result, it seems to the reviewer that. all gymnosperms re- 
semble one another in very many and very significant ways. On 
the contrary, it is the araucarians alone that present anything more 
than very slight resemblances to the lycopods, and even here the 
significant points of resemblance are few and less exact than the 
numerous ones that relate them to other gymnosperms. 
2. THE ARAUCARINEAE RESEMBLE THE CORDAITALES MORE 
CLOSELY THAN ANY OTHER CONIFERS.—Among those who hold this 
view no one has expressed himself more clearly or strongly than 
Scott, who says: ‘“‘The Araucarineae present a close agreement 
with the Cordaiteae in the structure of the stem, and particularly 
in that of the wood, which, as universally admitted, is often indis- 
