g2 BOTANICAL GAZETTE [aucusT ” 
change. When the integument and nucellus become free only in the : 
region of the nucellar beak, the inner set of vascular strands is shifted — 
from the peripheral region of the nucellus to the inner fleshy layer, : 
and this situation persists among the cycadophytes. Curiously — 
enough, it reappears in Gnetum, but in that case it is associated : 
with the presence of the two integuments. Among Ginkgoales the — 
outer set of strands is suppressed; among Taxaceae the inner set — 
is suppressed; and among Pinaceae both sets have disappeared. — 
The general tendency, therefore, is to eliminate the vascular strands 2 
from the ovule; but it is puzzling to find both sets absent from the — 
older Abietineae, and one set still present among the younger Tax- a 
ineae. 4 
The presence of a pollen chamber is one of the most conspicuous q 
features of the primitive ovule, and its association with fertilization by — 
ciliated sperms is so evident that it is natural that the two disap- — 
peared simultaneously with the establishment of Coniferales, but 4 
the abruptness of the disappearance is evidently more apparent than 
real. The presence of an extraordinarily deep pollen chamber in = 
Ephedra can hardly be regarded as a contradiction to this general ~ 
statement, for in that case it is evidently of secondary origin, asso a 
ciated with a remarkably massive archegonium neck. : 
THE FEMALE GAMETOPHYTE 3 
The female gametophyte of gymnosperms exhibits a progressivé 
series of changes which is significant because it leads toward the a 
angiosperm condition. At this point the very important historical — 
record fails, and the entire testimony must be obtained from living 
forms, which do not represent a series, but the ends of many series. 
For this reason, and also because such progress is always very uneq : 
in different forms, various stages of advancement may be expected 
to be found in forms grouped in a single alliance. The series, ther 
fore, is not so much one which conforms to recognized groups; as & 
series of stages each of which may be exhibited by members of various _ 
groups. . 
The general development of the gametophyte is quite uniform 
and since the same sequence of events occurs among the heterosporous- 
pteridophytes, it may be inferred that a knowledge of the ancient 
