18 P. ORPEN BOWER. 
During the development of this lateral organ, the cotyle- 
dons gradually increase in length, while the hypo-cotyle- 
donary stem also extends. The result of this is the gradual 
arching of the upper part of the seedling (fig. 3) till it bursts 
through the testa. The lower limb of the arch extends 
more rapidly than the upper. The cotyledons are thus with- 
drawn from the endosperm. The point of perforation of 
the testa by the stem is variable; it is usually on the oppo- 
site side of the seed from the hole made by the root, and is 
often quite separate from this (fig.4). In other cases the two 
perforations run together as a wide split of the testa (fig. 95). 
When freed the hypo-cotyledonary stem straightens itself, 
and now by its further extension the cotyledons are raised 
above the surface of the soil, and expand as green assimilat- 
ing leaves. The lateral organ, however, remains in close 
connection with the endosperm, and, growing further, com- 
pletely fills the cavity vacated by the embryo. 
That the lateral organ we have been describing is a 
means of transfer of nutrient materials from the endosperm 
to the seedling is proved by the following facts:—(1) That 
the endosperm still contains a considerable quantity of 
nutritious substances after the cotyledons free themselves 
from it. (2) That the cell walls of the outer cells of the 
organ are not cuticularised. (3) That it is not a perma- 
nently useful organ,since, when the endosperm is exhausted it 
also shrivels. ‘To express this view of its function, and at 
the same time avoid any term bearing with it a definite 
morphological idea, it may be called the “ Feeder.” 
We have seen that the plumule in the mature embryo 
consists of a simple papilla of tissue. When the cotyledons 
have expanded it appears, however, to have developed fur- 
ther. The time of this change I have not been able to 
ascertain accurately. In seedlings, such as those repre- 
sented in figs. 4, 5, the plumule consists of a pair of lateral 
leaves, decussating with the cotyledons; between these may 
be seen the apical cone (fig. 9). I have not, in any of the 
seedlings grown at Kew, cbserved any further development 
of the plumule than that described. The size and form of 
the plumular leaves of the oldest seedlings now growing at 
Kew may be gathered from figs. 7 and 8, which represent 
plants of ten and a half weeks’ growth. The cotyledons 
are,as stated, two in number. In one case (fig. 5) I observed 
three, but this may be explained by a splitting of one of the 
typical pair. Moreover, the position of the two smaller 
cotyledons in this case, with regard to the plumule, and the 
other cotyledon, makes this almost certain. 
