20 
E antes . — The Morphology of A gat his australis . 
free nuclei are scattered throughout the cytoplasm of the egg , and when wall- 
formation occurs the entire egg is segmented. In Agathis the free nuclear 
division invades only a small differentiated portion of the egg . Further, the 
cytoplasm of that mass is largely male in origin and not chiefly that of the 
egg. The only period when the egg-cell is wholly occupied by the pro- 
embryo is at the maturity of the latter, and then the filling has been accom- 
plished in a quite different manner — by the growth of cells that originally 
occupied only a small portion of the archegonium. That the proembryos 
are distinctly different in character is clear. 
■ In development and structure the proembryo of Agathis is unique 
among Gymnosperms (excepting, of course, the sister genus Araucaria , 
which from the little already known is undoubtedly closely similar). In 
other Conifers the preliminary proembryonic tissue is few-celled and situated 
in the base of the egg, where it has been formed from the products of 
a fusion nucleus which settled to that point. The few cells of this simple 
proembryo are very likely the reduced form of the similarly situated, more 
extensive structure of the Cycads and Ginkgo . In that only a small portion 
of the egg is selected for proembryonic development, Agathis is different 
from the lower forms and like its fellow Conifers. But from the time this 
method of reduction was chosen, the Araucarians have apparently followed 
a different path from that taken by the others. Effectiveness has been 
secured in the latter by great simplicity, in the former by great specializa- 
tion. A position in the bottom of the egg would not make readily available 
the supply of nourishment in the egg for the elaboration of the terminal 
cap. Hence possibly the fusion nucleus was retained in the centre of the 
archegonium. The embryonic cap need not be discussed further ; the per- 
fection of its structure speaks for itself. 
The suspensor cells of the Cycadales and the Ginkgoales, since derived 
from entire sections of the egg, form broad massive cylinders ; those of the 
Conifers, excepting the Araucarians, are more slender, but just as simple 
bundles. The suspensor group of Agathis differs from both these in having 
a double elongation, first in the direction opposite to that in which later 
expansion is to lead. Strasburger (12) has shown in Araucaria even greater 
specialization. The suspensor cells during their first elongation develop 
tubercle-like swellings or ‘ shoulders ’ which it is suggested aid in anchoring 
the base of the proembryo. 
Can the foregoing facts be considered as indications of a ‘ non- 
specialized embryogeny’, as Thomson (15) has suggested? All in all the 
morphology of the gametophyte and of the embryo proclaims for the 
Araucarineae a great amount of specialization, and strongly emphasizes the 
isolated position so generally conceded from the morphological and 
anatomical study of their mature sporophytes. Certainly on this evidence 
alone no close relation exists between them and the Cycadales and Gink- 
