M. Miiller on the Development of the Lycopodiacesc. 109 XIV. — On the Development of the Lycopodiaccae. By Kaul Muller*. [With five Plates.] [Continued from p. 40.] § 5. The perfect Plant. We have here to consider: — 1. the axis of the branch) 2. the roots of the branch ; 3. the leaves', and 4. the organs of reproduc-tion, 1. The axis of the branch. The germinating plant divides, as we have already seen, normally into two branches, consequently it is bifurcated. The same kind of division is exhibited throughout the whole gi'owth of Lycopodium denticulatum. The branches are always dichotomous, the vascular bundle always dividing in this manner. The branches, as is known, are compressed on the upper and under sides. Interiorly they are composed of numerous layers of cells. At first two circular spots are found in the centre, lying at some distance from each other. In these situations are produced the vessels, which as usual are surrounded by long," prosenchymatous cells (PI. III. fig. 12). They lie within the latter as a simple and almost circular group. From these vascular bundles proceed out-ward a number of tubular cells which finally come in contact with a layer of delicate and short parenchymatous cells. These last are the only cells throughout the whole axis of the branch which as yet contain any of the '^ cell-contents '^ (fig. 12 «), which consist of very small yellowish green granules, more or less collected into groups. The whole is inclosed by several layers of thin-walled, transparent and short parenchymatous cells. The layers situated most externally (the cortical layers) consist of cells which are always somewhat more elongated and more slender, and are not hexagonal, but have the form of parallelograms. Toward the terminal bud, the cells of the axis all become smaller and more crowded, till at last they look like mere globules (fig. 13). All these conditions vary in the most manifold way in the stems of the other Lycopodiaceae. This is especially the case with regard to the grouping of the vascular bundles. The structure of the cell-membrane also is very variable among them. These however are conditions of which a further examination would be extrinsic to my design. Most of them indeed are already known, and only individual cases require pointing out. The development * From the ' Botanische Zeitung,' Aug. 28, and Sept. 4, 1846. Trans-lated by Arthur Henfrey, F.L.S. &c.
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