VAILLANTIA HISPIDA 21 
remains undigested at the maturing of the fruit. (In Pl. 3, Fig. 2.) 
This mass is continuous with a thin layer of integument two cells 
in thickness, which surrounds the endosperm. The latter does not, 
contrary to the opinion of Hofmeister, break through the integu- 
ment, so that the envelopes of the mature fruit consist of the wall 
of the ovary lined by an integument (Pl. 3, Figs. 2, 24) two cells 
thick and loaded with starch. The endosperm cells up to a time 
when the embryo is large and approaching maturity, have thin 
walls. Starch accumulates more and more till the cells are gorged. 
Just before the complete maturity, however, the walls thicken so 
that in the mature seeds the principal foods stored in the endo- 
sperm are reserve cellulose* and starch. 
The central part of the endosperm is, up to the completion of 
the sphere stage of the embryo, continuous, so that the embryo 
lies in direct contact with the endosperm cells. When, however, 
the cotyledons begin to appear, the endosperm immediately sur- 
rounding the embryo breaks down, so that the embryo comes to 
lie freely in a cavity which is filled with fluid materials. The be- 
havior of the endosperm in this regard, as also the integument dur- 
ing the advance of the endosperm upon it, indicates the presence of 
digestive agent secreted by the embryo on one hand and the 
endosperm on the other. 
* The term “reserve cellulose’ is used here provisionally. The exact nature 
of the substance in the Ga/iene i is, 1 believe, not yet determined. 
