IN THE CLUSIACEÆ, MAGNOLIACEÆ, ETC. 89 
Endlicher calls it a fleshy raphe, but this origin is evidently due to the same source as 
that of the outer tunic of Magnolia. 
It is here necessary to point out the distinction between the different kinds of arilli- 
form coatings of the seed. We have strong evidence to show that the scarlet covering in 
the Clusiee, Magnoliacee, &c., is derived from a growth of the placentary sheath, which 
is a production of the funicular cord, whose origin is coæval with the anatropal inversion 
of the ovule: other cases however occur, where another still more exterior development 
is generated at a subsequent period: this is well known to proceed from the main 
placenta, or more often from the short funicular cord, which is the foot-stalk of the 
placentary sheath by which the ovule is attached, sometimes forming a thick cup as in 
the Sapindaceæ, &c., or at other times extending itself like a fleshy, coloured plane sheet 
completely enveloping the seed, as in the Tovomiteæ, or which form branching fleshy 
segments embracing the seed, as in Myristica, Samydaceæ, &c. These several varieties 
derive their origin from a growth of the placenta and are not developed from the 
original coats of the ovule; they are therefore arilliform in their nature, but as they are 
produced under different cireumstances, I propose to confine the term aril (arillus) to the 
kinds of coating last described, always void of spiral vessels, and to denominate that sort 
found in the Clusiee, Magnoliaceæ, &c., the arilline (arillinus), in which the vessels of 
the raphe are always imbedded. Both may and often do exist at the same time, in the 
same seed, or they may make their appearance independently of each other. Å 
There is said to be still another kind of extraneous fleshy coating, produced over the 
testa in the manner first pointed out by St. Hilaire, to which he gave the name of false 
aril, and which was afterwards ably investigated by Dr. Planchon, who substituted for it 
the name of arillode*. This tunic is described as originating in the expansion or rever- 
sion (dedoublement) of the mouth of the exostome or foramen of the primine, which 
gradually extends itself over its whole surface, and forms an extraneous envelope around 
the testa. The formation of the arillode from such a source, rests upon the authority of 
Dr. Planchon, to which Lattach its due weight; and although in support of his views, he 
described, with great minutenesst, the gradual formation of the arillode in dm | 
latifolius, it is certain that in drawing the conclusion that the arillode proceeds from the 
extension of the exostome, he expressed at the same time some misglving on the subject. 
Examining therefore the details as there represented, and COMPARE, these ke E zem 
. A 1 e $ 
observations on the seed of Euonymus, I think it may be inferred, with equal, if not wi 
d Idem, p. 7. 
* Mem. ante cit. p. 10. T : tire ai-j rifié 
t “En disant que ce dernier sac (le faux arille) procède uniquement de — er : ter aem des 
l'exactitude à la clarté. Comme l'ombilic, en effet, est très voisin du — Sp - solution de continuité. 
bords de ce dernier, devrait rencontrer dans le funicule un obstacle à son extension et 
une partie 
Mais c’est 14 au contraire que P expansion est la plus épaisse, et même elle adhère avec la base du raphe sur une p 
å G jerni ie. Il faut donc nécessairement, 
de sa longueur de manière à ce qu'elle semble sur ce point naître ae eni er ; = er funicule. Je crois 
pour expliquer une pareille disposition, admettre une soudure congeniale entre l'expansio EEE 
le mieropyle est fort dificile à voir, lorsqu 
dévoir ajouter pour prévenir tous les doutes, que chez les — erture, et la cache complètement : 
lovule est déjà très développé, parceque le faux arille est plissé — de son en des bords de P'exostome.” 
mais en détachant avec soin l'enveloppe accessoire, on peut facilement s'assurer que 
—Loc. cit. p. 9. N 
VOL. XXII. : 
