[ 81 ] III. Remarks on the Nature of the outer Jleshy covering of the Seed in the Clusiacese, Magnoliacese, 8fc., and on the Development of the Raphe in general, wider its various circumstances. By Joun Miers, Esq., F.R.S., F.L.S., Sfc. Read March 18th, 1856. IN a notice read before the Linnean Society on the structure of the seed of the Clusiacece, I described the external fleshy envelope of the seed of the Clusiece, and offered evidence to prove that this coating is a product of extraneous placentary growth, subsequent to the development of the primine, and therefore a kind of ariUus. It was of some importance to ascertain this point, as in the tribe Tovomitece of the same family, the outer coating, similar in substance and coloui', is unquestionably an aril : this is manifest from its peculiar form ; it is free from the testa, but may be opened out like a flat plate ; it is folded round the seed which it envelopes and conceals, its margins being fi-ee and overlapping one another : in the other tribe of the Garciniea;, this covering is also entire, is soft, and assumes the character of an enveloping jiulp. If, therefore, in the two latter tribes, the outer coating be unquestionably an aril, it was fair to conclude that the analogous envelope in the Clusiaoete is of a similar nature. This inference was still farther confirmed by the presence of a distinct simple raphe, which extends from the base to the apex of the seed beneath the inner peUicle of the aril ; it lies within a groove of the testa from which it is wholly free, the apex of which it perforates, and becomes lost in the chalaza of the inner integimient. Under the evidence of such demonstrative proof, as far as regards the Clusiece, I was led to institute a comparison of similar facts observable in the MagnoUacece, because, if that coating be considered an aril in the one family, it must be of the same nature in the other. I then referred to the admirable work of Dr. Asa Gray (' The Genera of the Plants of the United States '), where a diffei'ent view is entertained : here the external fleshy coat of the seeds of Magnolia is described as the testa, and its thick bony shell as the tegmen, or inner integument, the true tegmen having escaped the notice of that excellent botanist. In opposition to this view, I referred to the analysis I had made many years before, of the seed of Talauma, a genus intimately allied to Magnolia : the evidence then collected, convinced me that the ' testa ' described by Dr. Gray is arUliform, and that his ' tegmen ' is the true testa. If we examine this outer coating in Talauma, where it is entire, we find it easily detached from the testa or osseous shell ; and if we begin to pull it away fi'om the summit, the raphe, as a distinct cord, wiU be seen quite free from it, as in the Clusiece, and to lie in a corresponding groove which extends from the base to the apex : the upper end of this raphe is seen to penetrate an aperture near the summit of this osseous shell, and to become lost in the dark-coloixred chalaza of a membranaceous inner integument. To all appearance, the raphe thus seems quite free ; but if we examine it more attentively, a corresponding portion of the extremely VOL. xxn. M
III. Remarks on the Nature of the outer fleshy covering of the Seed in the Clusiaceæ, Magnoliaceæ, &c., and on the Development of the Raphe in general, under its various circumstances
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