CONTRIBUTIONS TO BOTANY. 
237 
in a deep groove upon the dorsal side, then crosses over the 
chalaza without any apparent interruption in its course, and 
returns down the ventral side in a direction close to the median 
line of the other cotyledon, till it again reaches the hilum. 
As this structure is at variance with recorded descriptions, it 
is necessary to state the circumstances more in detail. My first 
observations were made upon the dried seeds of Rhamnus cathar- 
ticus : this seed is smooth, of a hepatic brown colour, and of a 
flattish oval shape, somewhat tapering to the base, where it is 
callous and more polished ; it is a little angular upon the ven- 
tral face, and rounded upon the dorsal side, along which is seen 
a line running from the apex to the base : on pressing it, this 
line is found to be the margin of a deep chink, which extends 
all the way down to the axis of the seed. If we carefully remove 
the outer coating, we find it rather thin, very brittle, and crus- 
taceous, thus exposing a second tunic, which is very fine in 
texture, membranaceous, and polished , and upon its ventral 
side, opposite to the dorsal chink, is seen a distinct line running 
from the base to the apex, where it passes over a large areolar 
disk, and runs into the summit of the chink in continuity with 
the main cord of the raphe. If we take another seed, and cut 
it in two transversely, we see the outer brittle tunic just men- 
tioned becoming somewhat thicker as it approaches the dorsal 
chink, where it is continued by induplication, in the form of two 
rather thick crustaceous plates that line the sides of the chink, 
the internal edges of these plates being quite disconnected with 
each other : it is evident, therefore, that this outer covering is 
not an entire tunic ; for if it were unfolded, it would be found to 
be merely a thin plate with thick margins, which are introflected 
in the manner described. In the bottom of the chink, which 
widens towards the axis, is seen a thin membranaceous dia- 
phragm, that forms one side of a square hollow cavity which 
runs through the axis from the apex to the base, and which 
diaphragm is found to be a portion of the second thin polished 
membranaceous tunic before mentioned, that lies beneath the 
outer crustaceous covering ; and upon this diaphragm is observed 
the thick cord described by botanists as the dorsal raphe, which 
rises from the base, crosses the disk-like areole in the summit, 
and runs down the opposite side of the seed, forming the line 
first described as seen on the ventral face. The whole of this 
intermediate integument, with its entire raphe, may be exposed 
to view if we chip away in small fragments the outer crustaceous 
coating with the point of a knife, when the two cords, both ven- 
tral and dorsal, are distinctly seen ; the two teguments are closely 
adpressed upon each other, except over the ventral cord, where 
there is always a considerable interval between them, thus show- 
