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CALLIPELTIS CUCULLARIA 31 
the exception of those which occupy the middle portion of the 
endosperm and the layer of absorbing cells next the raphe. The 
endosperm continues however to grow, and ceases only when there 
is left of the integument only a single layer of cells separating the 
endosperm from the pericarp. The limit of growth in extent being 
reached, the cells commence to secrete reserve cellulose. Their 
lumina, by reason of the accumulating cellulose, become more 
contracted and rounded in form. The increase of cellulose is ac- 
companied by an evident reduction of the starch content, though 
a plentiful, supply is present at the maturity of the seed. 
The immediate supply of food necessary for the endosperm is to 
be found in the integument, of which the starch content is gradually 
increased as it reaches its maximum size. When the seed is ripe, 
a single layer of integumental cells only is left, excepting an 
island of tissue underlying the termination of the vascular tissue of 
the funicle. The endosperm is thus a concavo-convex mass, sur- 
rounded by an integumental membrane, this, in turn, being closely 
invested by the pericarp four cells in thickness (øl. 6, fig. 72). 
A considerable amount of starch is found in all the cells of the 
integument, particularly in the chalazal island. 
DEVELOPMENT OF THE EMBRYO 
As already pointed out, the embryo remains unicellular till the 
endosperm nuclei have reached the number of èight to sixteen, 
when it begins to develop rapidly, one transverse division follow- 
ing another until the embryo is composed of a cell row of ten or 
a dozen cells (p/. 6, fig. 6). The largest of these are in the sus- 
pensor. The terminal cell, the fundament of the embryo proper, 
is the smallest. The suspensor cells bulge out more or less. A 
portion of the suspensor may be composed of two rows of cells 
)۸ 6, fig. 9), though, whether this is due to 6 division 
or to displacement by longitudinal pressure, I cannot say. Prob- 
ably, however, the latter. The arrangement and number of cells 
in the suspensor is by no means constant, so that it is a matter of 
physiological significance alone. By further growth, the bulging 
suspensor cells extend themselves, so as to lie between the endo- 
sperm cells, but do not cause any destruction. They are filled 
with cytoplasm, and have large active nuclei, The development 
