6g 
Reproductive Structures in the Po do carp ineae. 
A monophyletic conception of the order, however, seems much more 
in accord with what we know of the history of the Coniferales, and they 
have been considered by almost all investigators to be a natural group 
descended from a single source. If this is true, their ancestors must either 
have been single-scaled forms, from which the double-scaled families of 
to-day have arisen, or else the cone with double scales is primitive, and has 
given rise to that with a single scale by reduction. 
The former view has been adopted by several writers, notably by Stiles 
in a recent paper, and is apparently shared by Miss Gibbs as well. The 
primitive cone among the Podocarpineae, and apparently among the 
Araucarineae also, is believed to have consisted of many spirally 
arranged sporophylls, in the axil of each of which was a single erect ovule. 
Pherosphaera , among living Conifers, seems most closely to approach 
this hypothetically primitive condition. The first sign of the ovuliferous 
scale was the appearance of an epimatium, inconspicuous and poorly 
developed at first, as in Microcachrys , Saxegothea , and some species of 
Dacrydium , but becoming larger until in Podocarpus y the most recent genus 
of all, the ovule is borne on the epimatium, which has been carried up on 
a stalk and is almost free from the ‘ scale \ In some such way as this the 
free ovuliferous scale of the Abietineae is supposed to have arisen, and the 
family is derived from a podocarpean-araucarian plexus. The living 
Araucarineae have departed from their Pherosphaera-Ytke prototype only in 
possessing an inverted instead of an erect ovule. 
This view of coniferous phylogeny will doubtless appeal strongly to 
those who believe that the Araucarineae are the most primitive members of 
the order, but the adoption of it necessitates an entire overthrow of the 
brachyblast theory of the ovuliferous scale of the Abietineae, which has 
until recently met with almost unanimous acceptance. This theory is well 
supported by facts, for, in addition to the mass of evidence derived from 
abnormalities, the vascular structure of the upper scale resembles precisely 
in its origin an axillary shoot. Much more cogent evidence than has yet 
been presented will be necessary to convince many persons that the ovuli- 
ferous scale of the Abietineae is only a glorified epimatium, and that its 
independent vascular supply represents merely a basipetal development of 
the ovular bundles. The homology between ovuliferous scale and epimatium 
is now pretty generally admitted, but the presence of the epimatium is 
logically accounted for only if it is derived from an axillary ovuliferous 
scale. To consider it a fortuitous outgrowth from the ventral face of the 
bract is not to explain it satisfactorily. 
The other alternative, which regards as most primitive a cone with 
distinct double scales, resembling that of the living Abietineae, appears to 
the writer much more in agreement with all the facts. According to such 
a conception the epimatium is a vestige of the ovuliferous scale, not its 
