Reproductive Structures in the Podocarpineae. 7 1 
that of the Abietineae, for in both groups the microsporophyll bears but 
two sporangia, a very different condition from that obtaining in the Arau- 
carineae, where the pollen-sacs are often very numerous. In fact, the 
Abietineae and Podocarpineae are the only Conifers which never have more 
than two microsporangia to a sporophyll. 
These two families are also distinguished from all others of the 
Coniferales by the possession of winged pollen-grains, and attention has 
already been called to the strong resemblance between the whole male 
gametophyte of Podocarpus and that of the Abietineae. 
Now that the investigations of Eames (3) in Agathis australis have given 
us a much fuller knowledge of the araucarian female gametophyte and 
embryo, we are able to compare the reproductive histories of the 
Araucarineae and Podocarpineae, and to observe their many points of 
difference. In the Araucarineae the megaspore membrane is poorly de- 
veloped, the archegonia are very numerous and distributed over the whole 
upper portion of the embryo sac, and the fertilized egg develops in situ and 
gives rise to a proembryo furnished with an elaborate protective cap, such 
as is found nowhere else. Among the Podocarpineae, on the other hand, 
the megaspore membrane is conspicuous, the archegonia are fewer in 
number and gathered in an apical group, and the products of the fertilized egg 
sink directly to the bottom of the archegonium, where they produce a pro- 
embryo very similar to that found among the Abietineae and their allies. 
Indeed it is to the type occurring among these dominant Northern Hemi- 
sphere Conifers that the whole female gametophyte of Podocarpus and its 
family conforms, and it shows little similarity to that of the Araucarineae. 
It is highly improbable that so many strikingly similar reproductive 
structures, both sporophytic and gametophytic, should have arisen in two 
independent groups and along two quite distinct lines of evolution. We 
are, therefore, forced to adopt the hypothesis that the Podocarpineae, and 
especially the genus Podocarpus , are more nearly related to the Abietineae 
than to any other family of the Coniferales, and since a great body 
of evidence is accumulating in support of the view that the Abietineae are 
the most ancient members of the Coniferous Order, Podocarpus must be 
considered as a relatively primitive type and the oldest genus of its family. 
The resemblances between the Podocarpineae and the Araucarineae are 
best explained as an inheritance of structures and tendencies from a very 
ancient group, ancestral to both and closely abietineous in affinities, from 
which the modern Araucarians have widely departed. In fact, it is perhaps 
more logical to consider the Araucarineae as derived from, rather than 
having given rise to, the Podocarpineae. 
This hypothesis as to the phylogeny of the Podocarpineae has the 
advantage of explaining more facts than does any other which has been 
put forward. 
