Seed in the Scitaminecie. 
23 
integument now begins to bend downward into the body 
of the nu cell us, thus giving rise to the micropylar collar 
which surrounds the apex of the embryo-sac, as in 
Canna and Thalia. The outer face of this collar shows the 
characteristic inner layer of the seed-coat, but this layer 
disappears at the edge of the fold which forms the collar, 
so that its inner face remains thin. Meanwhile there is 
formed just over the embryo-sac, from tissue of the outer 
integument, and around the micropylar remnants as a centre, 
a circular lid whose edge abuts on the upper margin of the 
collar (g. Fig. 48). In the adult seed this lid is a firm, resistent 
tissue, and rests upon the edge of the testa so as completely 
to close its opening, without being in organic continuity with 
it. Thus the embryo is well protected, yet is able to push out 
the lid easily, when germination begins, since no dense tissue 
requires to be ruptured. 
At fertilization the chalazal end of the inner integument 
lies about transverse to the axis of the nucellus (Fig. 45)- 
Soon it begins to turn upward, and at length a small part of 
the end of the integument stands almost at a right angle with 
the adjoining portion (Fig. 46). The tissue enclosed within 
this upturned end becomes specially differentiated, while the 
integument itself becomes compressed, as elsewhere. A con- 
tinuation of the inner layer of the outer integument is developed 
as far upward as the inner integument extends (int., Figs. 48, 
49). The cells of that part of the outer layer lying over this 
region become thicker and much shorter, so that they form 
here a palisade-like layer much denser than on other parts 
of the surface. This peculiar discoid patch at the chalazal 
end of the seed is plainly evident to the naked eye. The 
bounding layers of the region are lined by a double layer of 
cells with thickened walls, and within these, and filling most 
of the region, is a compact tissue of small thin-walled cells 
( ch . m.) Fig. 49). The possible significance of this peculiar 
development of chalazal tissue will be discussed later. 
Within the seed-coat the cells of the perisperm are con- 
siderably elongated {psp., Fig. 49 a); but toward the centre 
