IN THE CLUSIACEÆ, MAGNOLIACEÆ, ETC. 95 
admirable figures, of the growth of the ovule recorded in the valuable Memoirs of 
Brongniart and Mirbel, and, as will be seen, proved by the observations of the latter, 
cited in the foregoing page. It is not more unreasonable to conceive that the osseous 
deposit, forming the crustaceous covering, may in some cases be secreted in the arilliform 
coating, as well as in the primine of the ovule; in both instances, the secreted matters 
must pass through the same channel, and be supplied by the same vessels of the funicle, 
and such depositions at one point, instead of another, are probably regulated by the 
nature of the pre-existing tissues. In Zanonia and Fewillæa, the arilliform nature of the 
outer coating is better shown by the membranaceous state of the tunic, which is extended 
like a winged covering over the seed. 
From these circumstances we may infer, that the arilline need not necessarily be always 
fleshy in its nature, as in Magnolia; but that it may be either membranaceous, gela- 
tinous, coriaceous, or even osseous in its structure. Thus I have found from the position 
of the raphe, that the hard highly-polished tunic of the seeds of Drimys and Ilicium, 
usually regarded as testa, should be held to be a true aril: thus also the coriaceous 
coatings of many seeds will in like manner be found to be arilliform in their origin. Of 
that kind of seminal coating where the arilline is intimately combined with the testa, and 
where the raphe, greatly branched, lies imbedded between them, forming a compound 
tunic analogous to the structure already described in the Tovomiteæ, a very remarkable 
instance occurs in the Oleace@, where the raphe, instead of being spread into numerous 
branching nervures, exhibits itself by infinitely minute ramifications, as a dense network 
of most delicate spiral vessels, crowded together into a cottony web, like that of a spider’s 
cocoon, and fills up the entire space between the testa and arilline ; these tunics, aided 
by this interposition, are closely agglutinated into an apparently simple coating, but by 
maceration they may be separated from each other, and the interposed network may be 
drawn out into innumerable elegant spiral threads. This structure I have found in 
Tessarandra and Olea, and it probably exists in other genera of the family. Nearly the 
same development occurs in Caswarina, where a thick web of spiral fibres is found inter- 
posed between the crustaceous testa and the outer membrane, which is extended over it 
in the form of a wing. This structure, noticed many years ago by. Mr. Brown, and at 
that period described as a singular occurrence (Gen. Rem. p. 40), has since been confirmed 
by Schleiden, and figured in Schnitzlein’s ‘ Ieonographia " (Gen. 86). The Bu 
coating of the seed, here extended in the me wing, m covers the excessive deve- 
lopment of the raphe, will probably be found to be an arıllıne. = ÅT 
We have a = illastration of the arilliform nature of the external coating på p 
under somewhat variable forms, in the Passifloracee. In Tacsonia puma — hh 
the seed invested by a mucilaginous pulpy envelope, ee se pe 
i i i siderable vacant space between it and the osseous 
vesicle, quite detached, leaving å con der in gii: this 
testa, in every part save at a small point at the and the ar 
pellicle Te = vessels of any kind, except in its longitudinal raphe, Mee ^ P 
in its substance, appearing as a prominent white nerve, running ig e p 
the summit, where it finds a passage through a caruncular spot (the ; m i p7 
of the testa, beneath which it becomes lost in the chalaza of the inner integument. 
