CONTRIBUTIONS TO BOTANY. 
249 
coats of Magnolia, to which I have just alluded; and upon this 
supposition, the brittle covering of the seed of Alphitonia would 
consist of the endodermal lining of the endocarp, which becomes 
separated from it under the form of a resilient membrane. We 
have, however, strong evidence to prove that no such occurrence 
has taken place ; for if it had, this tunic ought to exhibit on 
its ventral face the same sutural line of dehiscence that the 
endocarp does; on the contrary, we find the ventral face of that 
tunic perfectly entire, though marked by the impression of the 
hollow sutural line of the endocarp ; and we notice an aperture 
in its apex, often continued some way down the dorsal face, and 
find that this opening does not form a sutural line, but that its 
margins are sinuous and overlap each other. It is therefore 
quite manifest that, if this tunic belong to the pericarp, it cannot 
be any resilient portion of the endocarp. 
Under the second mode of viewing this question, that it is a 
distinct formation, much evidence, in the way of analogy, may 
be drawn from other well-known cases ; but I will refrain from 
entering into this consideration at present, as I shall on a future 
occasion discuss the nature of other .adventitious coatings within 
the pericarp of seed-vessels, which seem to originate in peculiar 
depositions, or in the growth and expansion of the placental 
surface. Among the many kinds of development of this 
class, which seem to have attracted little notice, may be men- 
tioned the pulpy sacs in which the seeds of Cucurhitacea are 
severally enveloped, each sac being attached to a distinct bundle 
of tracbeal vessels branching from the broad placental lamime, 
as described by St.-Hilaire*, where these pulpy sacs are at first 
solid and fleshy, and afterwards become liquid and mucilaginous. 
A veiy similar growth is developed from the placentary plates of 
the fruit of Adansonia, where a thick deposit is formed around 
each seed. LeguminoscE, too, offer numerous examples of analo- 
gous growth. The large ball of elastic silky hairs that envelope 
the seeds in Bombaoc and other kindred genera derives its growth 
wholly from the pericarp, and not from the seeds. In nydro- 
phyllum and EUisia (Gaertn. pi. 110 & 184), the placenta grows 
round the seeds, which it soon encloses entirely, and fills the 
cell of the fruit. When the capsule bursts, this development 
looks like an internal coccus, assuming the appearance of a 
resilient endocarp, which opens into two valves corresponding 
with those of the capsule; and to the inner surface of these 
placentary valves the seeds are parietally affixed. 
As regards the general structure of the flower in the Colle- 
tiea, there is little to add beyond what we find recorded on the 
subject ; but it may be remarked that the lobes of the calycine 
* Mem. Mus. v. 306. 
2 K 
VOL. I. 
