234 
CONTRIBUTIONS TO BOTANY, 
layer of cellular deposit of spongiose texture, brittle when dry, 
and so loosely aggregated that, when removed and soaked in 
water, and then slightly touched, these cells separate into di- 
stinct globules of a hexagonoid shape, and of a deep crim- 
son colour. In the substance of this second membranaceous 
tunic is observed a white cord, which rises from the bottom, 
originating in one of the angles of the basal pervious chink, 
runs up one side of the tunic, crosses its summit without inter- 
ruption in its course, and passes down the contrary side, termi- 
nating in the opposite corner of the basal perforation, and thus 
making a complete peripherical circuit round the inner surface 
that lines the shell. This coi-d is composed of a number of 
delicate spiral threads, so free that each fibre is easily drawn out 
separately. In some genera of the Rhamnacece (as in Zizyphus, 
Alphitonia, &c.), this second tunic is perfectly free from the 
outer corneous shell, a considerable space existing between them, 
in which is generally found a small quantity of very lax white 
cellular tissue. • A third integument, although free from it, fills 
the space in the upper moiety of the last-mentioned coating in 
Colletia, but a little below the middle it becomes gradually 
narrower, more opake, and of a thicker texture, until it 
tapers into a short stout thread, that terminates in the basal 
perforation of the outer shell. The opposite extremity, or sum- 
mit, is marked with a dark fleshy disk, like a chalaza, of nearly 
its own diameter. These integuments closely invest the albu- 
men, which is fleshy, homogeneous in texture, and of consider- 
able thickness on the ventral and dorsal faces, but becomes 
very thin round the margins of the cotyledons, the whole 
mass being of a roundish oval shape, suddenly contracted at its 
base into a prominent nipple, which is enclosed within the ros- 
tellated neck of the investing integuments before described; the 
embryo is nearly the size of the albumen, and much flattened, 
the cotyledons being oval, foliaceous, and fleshy, slightly cordate 
at the base, where they are united by a short eylindrical radicle, 
one half of which- lies within the sinus, the other half in the 
nipple of the albumen ; the cotyledons are anterior and posterior 
in regard to the axis of the fruit. 
The presence of the distinct external crustaceous shell, always 
more or less pervious at the basal extremity (or one of its sides), 
and the position of the raphe, as above described, attached to an 
intermediate integument, making nearly a complete circle round 
the seed, — are features that occur not only in all the Colletiece, 
but in all the genera of the Rhamnacece that I have examined, 
though subject to several modifications, which I will mention. 
In Rhamnus catharticus, however, as well as in R. Alaternus and 
a few others, the raphe, though still peripherical, is difi’erently 
