CONTRIBUTIONS TO /BOTANY. 
147 
parts, except at the periphery of the flattened plate, where it is 
attached to them by means of a very distinct cord or raphe filled 
with numerous spiral vessels. This raphe is observed both in 
the vertical and transverse sections, where it forms a broad 
hollow tube partaking of the nearly circular shape of the cavity, 
the inner surface of the tube being lined with a close web of 
white spiral vessels ; it is seen to originate at one of its extremi- 
ties in the hilar foramen of the outer tunic, and after making 
nearly an entire circuit, it returns close to its starting-point, 
where it disappears in the chalaza of the inner integument, over 
the nidular place of the embryo. The embryo is very small, and 
is best seen in the longitudinal section, where it is found im- 
bedded in the albumen in the extremity of the lower leg of the 
horse-shoe, or that nearest the hilar foramen of the outer tunic : 
it lies somewhat obliquely, with its tadicle pointing outwards to 
a small external prominence of the albumen, and with the coty- 
ledons directed towards the centre of the seed : the radicle is 
terete, short, obtuse, and of the length and breadth of the coty- 
ledons, which are pointed and much compressed, its whole length 
being twice its own diameter, and about length 
of the seed. 
On examining this evidence, we readily discern the nature of 
these several parts : the inference that the outer tunic, which 
has hitherto been denominated the testa, is of extraneous origin, 
and therefore of the nature of an arillus, is supported by four 
reasons : — 1. Because it is not likely that the fungous plate, or 
large funicular expansion found within the cavity of the seed, 
could have found its way from the exterior into the hollow space 
through the small hilar foramen of the outer coating ; on the 
contrary, it is more reasonable to conclude that this outer tunic 
must have been a subsequent formation after the ovule had 
become convoluted round that excentrically expanded support. 
2 . Because, had this tunic been the testa, that is to say, a simple 
development of the primine of the ovule, it would have exhibited 
some trace of its organic connexion with the other integuments, 
especially about the region of the chalaza, and would have par- 
taken of the same form, and have been drawn along with them into 
the cavity. 3. Because this outer tunic is not only completely 
free from all contact with the raphe, but is far remote from and 
exterior to it, and therefore it must necessarily have been of a 
growth posterior to the curvature of the ovule. 4. Because the 
integument resulting from the growth of the primine is indicated 
beyond all doubt by the pr'esence of the cord of the raphe within 
its substance : it is the more fleshy and exteidor of the two 
integuments which immediately invest the albumen, follow- 
ing it in its excentric curvature, and adhering along the 
