156 BOTANICAL GAZETTE | SEPTEMBER 
14. Gamopetaly, from small beginnings, has increased rap- 
idly to the present. 
15. Hypogyny has measurably decreased, while epigyny has 
correspondingly increased. 
GENERAL RESULTS FROM EMBRYOLOGY (ONTOGENY. ) 
After fertilization, the oosphere in all angiosperms divides 
transversely into two parts, one of which becomes the so-called 
‘“‘suspensor,’’ and the other the embryo proper. The suspensor 
segment may remain undivided, or it may undergo one or more 
divisions. The embryo segment at once, or after one or more 
longitudinal divisions, becomes divided by a transverse wall 
which separates the foliar (terminal) from the cauline (central) 
cell or cells. Soon walls form parallel to the surface of the 
growing embryo, giving rise to a distinct outer layer, the derma- 
togen, which covers all except the lowermost part of the grow- 
ing plant. A little later the inner cells of the cauline portion 
become differentiated into plerome and periblem. Finally, the 
formation of the root and the root-cap are essentially the same 
in all angiosperm embryos. 
The development of the embryo is so nearly the same in the 
two sub-classes, that we are compelled to admit their close rela- 
tionship. The only histological difference which is measurably 
constant is that the longitudinal division of the embryo takes 
place before the formation of transverse walls in dicotyledons, 
and afterwards in the monocotyledons. To this general rule, 
however, there are numerous exceptions. 
If we study the subsequent development of the embryo it is 
found that the terminal cell, which remains for some time undi- 
vided, usually produces a single foliar structure (cotyledon) 
which is situated terminally upon the caulicle, and that the ter- 
minal cell which undergoes early longitudinal division gives rise 
to two foliar structures (cotyledons). Whether the formation 
of one or two cotyledons is dependent upon the direction of the 
separating walls cannot be discussed here. It is at least an 
interesting coincidence that in the young embryo the undivided 
