449 
of the Endosperm during Germination. 
cotyledon ; but as the cotyledon increases in size, the sphere of 
action of the ferment gradually extends towards the periphery of 
the seed until all the tissue has been attacked and the cotyledon 
completely fills the whole of the space previously occupied by the 
endosperm. 
The progress of the ferment action in the case of the germina- 
tion of the seed of Tamus may be described as centrifugal with 
reference to the embryo, since the ferment, which apparently 
proceeds from the cotyledon, affects first those walls of the endo- 
sperm cells which are in immediate contact with it, and, as the 
cotyledon enlarges pari passu with the disorganization and absorp- 
tion of the endosperm, progressively extends its sphere of action 
into deeper layers. 
At any given stage of germination the ferment action is 
practically confined to a narrow zone of endosperm tissue, some 
three or four cells deep, immediately outside the cotyledon. 
The seed of Galium Tricorne, which was chosen as another 
example of a thick-walled seed for comparison with Tamus , offers 
quite a different type of ferment action during germination. 
Certain points regarding the general anatomy of the seed may 
first be described. The seeds of Galium Tricorne, which are 
closely invested by the dry pericarp, have, as is well known, the 
form of hollow spheres, slightly flattened on the ventral side, and 
on this side also, a pore is left which opens into the internal cavity. 
The curved embryo lies buried in the endosperm, with its radicle 
directed towards the basal portion of the seed 1 (Fig. 11). 
The endosperm is composed of thick-walled cells whose con- 
tents stain a deep brown colour with a solution of iodine in 
potassium iodide. Besides protoplasm and nuclei the cells con- 
tain aleurone grains, which, together with the cell walls, constitute 
the principal reserve materials. The cells do not shew any very 
definite shape or arrangement, though they tend to radiate 
outwards from the embryo. The walls are of varying thicknesses 
and are irregular in outline, and thus shallow pits occasionally 
occur, more particularly in those parts of the endosperm remote 
from the embryo. 
The thick and irregularly-pitted walls of the endosperm are 
richly provided with connecting threads, which are usually 
arranged in barrel-shaped groups, though scattered threads also 
occur. The threads, which are often beautifully curved, shew 
a well-marked median node. No distinction can be drawn between 
the groups of threads which occupy the pit-closing membranes and 
those which are found in the thick parts of the walls, for often the 
pits are only on one side of the cell wall (Fig. 16 ( y )). In such cases 
1 Lubbock, “On Seedlings,” vol. ii., figs. 439 — 441. Le Maout and Decaisne, 
p. 483. Engler and Prantl, Pflanzen-familien, iv. 4, p. 150. 
