[ 415 ] XXXV. On the Origin and Development of the Pitchers of Nepenthes, with an Account of some new Bornean Plants of that Genus. By J. D. Hookek, M.D., F.B.a. 8r L.s. 8rc. Read June Ifith, ISoS. In a paper read before the Linnean Society on the 16th June, 1857, and published in this volume of the ' Transactions ' (p. 137), I mentioned, in a note, that I had examined and prepared drawings of the development of the pitchers of Nepenthes, from plants in the Royal Gardens at Kcw, and that these coniii-mcd Griffith's observation * that the pitchers are modifications of the cxcurrent midrib of the leaf. I have now the honour of laying before the Society the principal facts observed during the examination in question, wliich have further led me to the conclusion that the pitchers are modifications of a gland situated at the apex of the midrib of the leaf; and I have added the necessary illustrations. I shall also append to this paper an account of the most singular and gigantic plants of the Order, which have lately been discovered by H. Low, Esq., on the lofty mountain of Kina Balou in Borneo. Part I. — On the Development of the Pitchers o/" Nepenthes. At the earliest period at which I have examined the undeveloped leaf of the full-grown plant of Nepenthes Icevis of our gardens f, I find it to consist of a minute, blunt, conical body, about xo^th of an inch long (Tab. LXXIV. fig. 1 b), with a slight longitudinal depression on the anterior surface, leading to a shallow oval cavity, which is placed imme-diately below the apex. At this period the cuticle is scarcely distinguishable, but the oval depression has a more shining appearance and less defined superficial layer of cells than any other part of the cone. On a vertical section carried down and through the groove and oval depression (fig. 2), the whole substance is foxmd to be formed of a rather dense parenchyma, becoming looser, and as it were deliquescent at the oval cavity. Tliis oval cavity is all that represents the future pitcher, and it is simply a subterminal gland. The next period (as defined by a marked progress in specialization) is that at which thei'e is an evident differentiation of the conical body into the lamina of the leaf and a superimposed body. At this stage (fig. 3) the cone is found to be prolonged upwards, and about a^oth of an inch long. The frontal groove is rather deeper, and has defined margins. There is an evident contraction about halfway between the base and apex, most marked on the edges of the groove. The apex of the cone projects forward and rather arches over the oval cavity, which has deepened, and is directed inwards and downwards. There is a * In 'Calcutta Journal of Natural History,' vol. iv. no. xiv. July 1S43, p. 231. t It is the iV. gracilis, Korth. I have to record my obligations to the Messrs. Low, of Clapton Nurseries, and Messrs. Veitch and Son, of the Exotic Nurseries, Chelsea and Exeter, for the liberal manner in which they have aided me by specimens of rare species in their establishments, for examination.
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