Embryo and of that of the Grass in particular. 5 1 7 
embryo ; the growing-point occurs at the region between the upper and 
lower halves of the embryo. In Juncus glaucus he found that after the 
terminal cotyledon a succession of sympodially-formed foliage-leaves occurs, 
each arising out of the sheath of the preceding one, before any other organ 
exists at all besides these leaves. He states that this mode of develop- 
ment in Juncus appears to contain the key to the understanding of the 
construction of all Monocotyledonous embryos, for there occurs here several 
times in succession what occurs only once in the first development of 
the terminal bud of every Monocotyledonous plant. He points out that 
Strasburger’s view that the ontogenetic development of the Monocotyle- 
donous embryo represents a 5 later adaptation ’, due to the cotyledon press- 
ing the stem-apex to one side, is contradicted by the fact that the later 
cotyledon with the later hypocotyledonary segment constitute a morpho- 
logical unity, completely corresponding to that of the Archisperms, which 
later becomes in its extension the shoot ; that there is thus not the slightest 
trace of a lateral sprouting of the cotyledon from a pre-existing axis. 
‘ That the axis exists before the cotyledon cannot be maintained, for it has 
no growing-point. On the contrary, the cotyledon exists before the com- 
mencement of activity of the growing-point. ... It exists, however, not as 
a cotyledon, but as part of a thallus, which becomes a cotyledon only after 
the appearance of activity of a growing-point.’ 
Hegelmaier also, in Canna indica , notes the development of the first 
three plumular leaves without there being any stem-apex present at all. In 
Pistia he found that seven or eight plumular leaves arose, each out of the 
base of the preceding, in a spiral sequence, with no sign at all of a stem-apex. 
He says : ‘ The clearly terminal position of the cotyledon is merely a single 
phenomenon in a whole group of such, but one of the most striking of the 
group, for the following leaves, which are equally with the cotyledon 
(relatively) terminal, are laid down in somewhat closer approximation to 
the preceding leaf-apex and thus form a gradual transition to the production 
of a so-called bud-axis with its own growing-point/ He says that if the 
theory of the cotyledon assuming the place of an aborted stem-apex be 
extended, as it ought to be, to the plumular leaves (which arise in the 
same way as the cotyledon) it would lead to absurdities. 
I would draw particular attention to the sympodial arrangement of the 
cotyledon and the first few plumular leaves in the embryos above-mentioned. 
It involves the complete absence of an epicotyledonary axis and of laterally 
placed leaves. Hence, neither the cotyledon nor the plumular leaves 
concerned can be lateral in position, and no evidence can be adduced 
to show that this is a secondary and derived condition of things. 
But the most fundamental evidence for the phylogenetically terminal 
position of the cotyledon has yet to be given. It rests on the sure and 
unequivocal basis of embryologicai data which are common to all the 
N n 
