founded on the Structure of their Seedlings . 69 
latter. There is no doubt that the phylum of Angiosperms 
has not sprung from that of Gymnosperms.’ 
The question so far then is open, and there is nothing in 
the present state of botanical knowledge to discredit the con- 
clusions which I have drawn from embryological evidence 
because they infer the superior antiquity of the seedling with 
two cotyledons. 
The development of the embryo within the seed has some- 
times been thought to show that the seed-leaf of Monocotyle- 
dons is a terminal member, and its plumule lateral. If this 
conclusion were well founded, it would be difficult to derive 
the Monocotyledonous embryo from a Dicotyledonous form. 
We should be almost forced to consider the one-leaved form 
as the more ancient. The two seed-leaves of a Dicotyle- 
donous embryo must then be derived from the splitting of the 
original terminal member. 
But the comparative work of Hegelmaier (14) and others 
has shown how little phylogenetic importance can be attached 
to details of structure in the embryo at this early age. In 
Corydalis ochroleuca , for example, there is a slight but un- 
doubted cleft in the embryo of the ripe seed which separates 
the cotyledons from each other, while in C. cava no such division 
exists. The embryo is Monocotyledonous from the first. 
The change from a Dicotyledonous to a Monocotyledonous 
habit must have taken place at a comparatively recent period 
in this case : more recent, that is, than the origin of Corydalis 
as a genus. Yet we know from the researches of Dr. Schmid 1 
that no traces of the original bicotyledonary structure are to be 
found in the early history of the embryo of Corydalis cava. 
The very careful observations of M. Sterckx (38, p. 42) 
on the embryo of Ranunculus Ficaria up to the period of 
germination illustrate the same point. I have already referred 
to them (p. 63), and will only say here that the history of the 
embryo within the seed throws little light on the homology 
of the single cotyledonary member. Nothing in its develop- 
1 Schmid, Beitrage zur Embryo-Entwickelung einiger Dicotylen. Bot. Zeit. 
1902. Abth. I. p. 207. 
