344 The British Association at Birmingham. 
the fertilised egg (a natural epoch, since a new generation dates 
from it) and ending with the formation of the ripe seed (a true 
physiological epoch, since it corresponds with a complete change in 
the conditions of life) would seem very well defined; but experience 
has shown that here, as in Zoology, embryologists lose more than 
they gain by dividing the subject in this way—-one group of investi¬ 
gators beginning their work where the others end theirs—and that 
this division is neither so simple nor so natural as it appears at first 
sight. It is not simple because the embryo is not always com¬ 
pletely dormant during the interval between the formation of the 
ripe seed and the first steps in germination. In most Monocoty¬ 
ledons and many Dicotyledons the embryo is an almost un¬ 
differentiated mass of meristem when the seed first ripens, and 
becomes differentiated internally and externally by degrees during 
the interval before germination : this is often called the maturation 
of the seed, and it is quite distinct from its ripening. Maturation 
is a process characteristic of the seeds of geophilous plants, which 
commonly lie in the ground for a year at least before germination ; 
the embryo of such plants is not comparable morphologically with 
that in the seed of an annual which may have ripened at the same 
time, since the embryo of the annual has root, stem, and leaves 
besides its cotyledons, and is ready to germinate immediately on 
the return of spring. Hence the morphologist must continue his 
study of the geophilous embryo throughout the maturation period 
if he is to compare it with that of the annual; even then he will find 
it less advanced than the annual embryo though both be examined 
as they break out of the seed, for the geophyte may, perhaps, be 
four or five years before it flowers, while the annual has to complete 
its whole life-cycle in a single season. The division of the subject into 
two parts, the first ending with the embryo in the ripe seed, is also 
an unnatural one, even if the time of maturation be included in that 
first period ; for the structure of the embryo cannot be completely 
understood by reference to its past alone. The observer must 
expect adaptive characters of three kinds:—(1) those imposed on 
the embryo in the past by its development within the embryo-sac 
while it is still parasitic on the parent plant; (2) certain adaptations 
to the process of germination itself; (3) characters which will be 
useful after germination. Before the utility of these characters can 
be fully understood, the development of the seedling must be 
followed for some time. In short, the structure of the embryo is 
dependent upon its future as well as on its past, and a division of 
the subject which excludes that future is, as Balfour says, purely 
artificial. 
The work done in recent years on the anatomy of the seedling 
has therefore not only completed Irmisch’s work on its external 
morphology, but has also thrown light on the problems of early 
embryology, attacked by Hanstein and his immediate followers. 
These problems are of two kinds, relating to the internal anatomy 
and the external morphology of the embryo. Hanstein himself 
was chiefly interested in the former, and his work disposed once for 
all of the possibility that the embryo of Angiosperms might possess 
an apical cell in the earlier stages of its growth as a reminiscence 
of its cryptogamic ancestry. One general result of work on the 
embryo since Hanstein’s time has been to discredit phylogenetic 
