1906] CHAMBERLAIN—OVULE OF DIOON 351 
the starch is soon dissolved. The change from starch to a soluble - 
form doubtless takes place repeatedly, because the starch at various 
Stages in the development of the archegonium is sometimes present 
"and sometimes absent. The protoplasm of the jacket cells is abun- 
dant and their nuclei are much larger than those of the surrounding 
tissue. The changes taking place within these cells and nuclei 
resemble those which occur in glandular cells, there being a period 
of accumulation, followed by discharge, and then exhaustion, after 
which the processes are repeated. Glandular activity begins in 
December, as soon as the archegonial jacket becomes distinguishable. 
At this time the protoplasm of the central cell consists of a thin periph- 
eral layer, and still thinner lamellae which divide the interior into 
vacuoles of various sizes, those near the center being the largest 
(fig. 36). The activity increases gradually up to the time of fertili- 
zation, about the first of May, and then diminishes. At the close of 
the period of free nuclear division in the proembryo, the jacket is not 
very vigorous, but there is still some activity. Toward the close of the 
intrasporal development of the proembryo, the jacket cells become 
weak in contents and begin to break down; and after the embryo has 
broken through the base of the egg and advanced 4 or 5™™ into the 
endosperm, the jacket is scarcely recognizable. During the period 
of repose or exhaustion (jig. 36) the protoplasm of the jacket cells is 
finely vacuolated. The nucleus has a somewhat homogeneous, 
finely granular structure, in which the chromatin is not conspicuous, 
although it can be seen that most of it is in the half of the nucleus 
nearest the egg. The protoplasm of the haustoria is evenly granular. 
As activity begins (fig. 37), the protoplasm of the jacket cells 
becomes more coarsely vacuolated and food materials of various 
shapes and sizes appear within it. The nucleus is particularly active. 
The nucleolus becomes saturated with a substance which stains black 
with iron haematoxylin, and the chromatin first becomes conspicuous 
and then obscured by a substance which also stains black and may 
© the same as that in the nucleolus. Material passes from the 
nucleus into the cytoplasm and from the cytoplasm into the haus- 
‘orla. Once within the haustoria, the food materials are already 
within the egg. In passing from the haustoria to the deeper portions 
of the egg, the materials break up into smaller and smaller granules 
