Nymphaacece .] flora inbica. 235 



in all its bearings: he considers — 1. That the two cotyledons may be regarded as 

 one split cotyledon j against which we would urge, that the plumule ascends directly 

 from between them, that the first pair of leaves are at right angles to them, and 

 that the relation of the plumule to these lobes differs in no way from what is seen in 

 other Dicotyledons, and is not like that of any Monocotyledon known to us. 2. lie 

 suggests'a comparison of the embryo with those of Jponogeton, Cymodocea, and Po- 

 sidonia. This we have made ; they are exalbuminous seeds, with strictly monocoty- 

 ledonous coleorhizal embryos, not contained in the sac of the amnios. Of these, 

 Aponogeton, the germination of which we have studied (see also Edge worth in Hook. 

 Journ. Bot. 1844, p. 405. t. xvii. and xviii.), has a linear plumule parallel to the 

 cotyledon, and lying in a narrow slit or fold of the latter. In Posidonia also the 

 cotyledon is longitudinally cleft on one side, and the plumule, which is lodged in the 

 slit, is inflexed. In Cymodocea the plumule is enclosed in the acute cotyledon. 

 3. Another supposed anomaly is founded on the cotyledons not being contracted at 

 their bases, and the plumule having an oblique position relatively to them ; the latter 

 observation, however, is not confirmed, and very many dicotyledonous embryos are 

 continuous with the radicle in diameter, or even taper upward from it. 



2. Germination. This we have studied in three species of Nymphcea, in Euryale 

 and Victoria, all of which present the same appearance, with little modification. 

 The radicle and bases of the cotyledons protrude through an orifice at the micropylar 

 end of the seed, caused (as explained by Tre'cul) by the falling away of a little oper- 

 culum opposite the radicle. The radicle turns downwards, and becomes a liliform 

 rootlet, or is sometimes altogether arrested. The body of the cotyledons remains 

 within the seed, and the plumule ascends from between their exserted bases, attains 

 a considerable length, and gives off two strictly opposite leaves at right angles to the 

 cotyledons ; of these leaves one has a vaginate petiole, with adventitious rootlets de- 

 veloped at its base, and a lanceolate lamina with reticulate venation ; the other is 

 reduced to a mere filiform subulate petiole, and has no rootlets. Within these first 

 pair of leaves two others are developed at right angles to them, the sheathing base 

 of the petiole of the lower embracing that of the upper, which is much the smallest ; 

 the first pair of leaves we hence consider to be opposite, and the following alternate. 

 Trecul, on the other hand, by calling the leaf reduced to a petiole the first, and the 

 larger one the second, would seem to imply that the first two leaves are alternate, or 

 developed at different epochs; but they are so strictly opposite (at the apex of the 

 terete tigellus) in the numerous specimens we have examined, and in all three genera, 

 that we are inclined to consider their dissimilarity in size to be due to unequal 

 development. In Nupiar lutea, however (which we have not examined), Trecul 

 describes the first leaf as springing at once from between the cotyledons, and the 



second from the axil of the first. 



Near the cotyledoiiary end of the radicle of Nymphtfo is a swollen ring, which 

 Lindley suggests may be analogous to a coleorhiza ; but this never forms a sheath to 

 the radicle, is not developed till the radicle germinates, and, a3 Trecul has shown, it 

 performs the office of adventitious rootlets, and hence its function commences when 

 that of a coleorhiza ceases. In Eur : U and Victoria it sends forth horizontal pro- 

 cesses, in all respects like rootlets, which perform the office of the radicle, which 

 most frequently in these genera does not elongate. The radicle itself invariably 

 decays soon after the leaves are formed, with the tigellus and remains of the seed, 

 and the plant is nourished by the adventitious rootlets at the bases of the petioles. 

 These rootlets emerge enclosed in a cellular sheath, which elongates considerably, and 

 at last tears away, leaving a tubular sheath at the base, and calyptra at tbe apex of 

 the rootlet. The formation of this and of the vascular bundles in the rhizome, root- 

 let, cotyledons, etc., are beautifully demonstrated in Trecul's papers, to which we 

 refer for their minute anatomy. Trecul considers that the cotyledons being retained 

 within the seed, and the radicle not becoming the root of the future plant, are both 

 indications of an approach to Monocotyledons. This is a point which we are not pre- 

 pared to discuss. We cannot, however, withhold an impression that neither of these 

 phenomena are confined to Monocotj dons ; but the point has not, so far as we are 



