near the apex. I shall not at present go into a full description of my observations. The apex consists of a firm and horny beak, which can be well felt by the tongue. Undoubtedly this beak acts the part of a perforator; it is in fact a bodkin for clearing a path for the plumule through the superincumbent soil. For this work the leaf is entirely unsuited, experiment showing that it cannot make headway through the clods. The coleorhiza or sheaths of the embryotic roots seem to have no organic value whatever, two or three roots sometimes coming out at one rupture. They are formed by the mechanical thrust of the radicles against the cellular envelope, as a baker might form sheaths on his fingers by pushing them through a sheet of dough. But the sheath of the plumule is not pushed; it has a temporary kind of growth, and the apex is frequently half an inch in advance of the point of the leaf.

Two more or less vascular rays (h) run up through the plumule sheath.* What the morphological significance of these rays is may be questionable. Are they the midribs of two leaves fused together at the edges? Or are they simply a provision for giving strength to the structure? Or are they the sources from which the beak derives its hardness and boring power?

In the underground rhizome of Triticum repens I have found the bud covered with as many as four closed sheaths enfolding each other. But they differ somewhat from the embryotic sheath, having many vascular rays all round. It can hardly be doubted, however, that in both cases the function, or at least one function of this sheath, is to act as a perforator. These rhizome sheaths can hardly be regarded as cotyledons, since no seed is present. And if the sheath enveloping the plumule of a germinating grass seed is the homologue of a rhizome sheath, is the embryotic sheath a cotyledon ?

But I will only further indicate a few points for inquiry.

* I have stated in "The Botany of Three Historical Records," p. 27, that "three stalks in initial stages may be seen in transverse sections of barley embryos." I now find that this is a mistake. What I regarded as two lateral buds in addition to the central bud or plumule, are in reality the two vascular rays running up from the embryo through the cellular substance of the sheath.

The scutellum (fig. 13) envelopes all those parts of the embryo not enclosed by the sheath. The sheath grows out of the scutellum. The scutellum differs in form in different grasses. The one here figured is that of the wheat; it ends. at the top rather abruptly. In the oat the upper end runs away to a slender point, a cross section of which is shown in figure 12. The lower portion of the scutellum is really an enclosing matrix of cellular albumen containing no starch. And while in a barley eight or nine radicles frequently exist before germination, and may be projected out by squeezing between glass plates, not a trace exists of what is called "the radicle." Down the middle of the upper extension (k) runs a vascular pencil or cord 7 (figs. 12 and 13), and from this cord to all appearance is evolved the embryo. To this I merely allude. But now, if the material of the scutellum or matrix is absorbed into the growing plant, the scutellum assumes one cotyledonary function-the nursing of the embryo.

Has the sheath any such function? Is any of its material absorbed from contact and pressure by the leaves? Or is it the duty of the sheath, like a nurse, to lead out the infant plumule while the scutellum, like a mother, supplies it with its earliest food?

To some of these points, when more fully matured, I propose to return.

Explanation of the Figures.-Plate XIX.

Figs. 1 and 2.-Oat and wheat plants where the seeds have been deposited about half an inch below the surface. The sheath of the plumule ends at c.

Figs. 3 and 4.-Oat and wheat plants where the seeds have been deposited from 6 to 10 inches deep. The sheath extends from a to c, or from b to c. Nodes are carried up to b, throwing out roots through the walls of the sheath.

Figs. 5 and 6.-Oat and wheat plants from seeds deeply deposited. The loops d show where the stalk, unable to push its upper portion along the sheath, has broken through, forming a fatal noose.

Figs. 7 and 8.-Show cases in which the loop, by the protracted growing of the lower part, while the upper part has stuck fast, has at last broken at e.

Fig. 9. A plant of maize, to show to what length the sheath will sometimes extend; it reaches from near a to c. The embryotic node remains in the kernel, throwing out the embryotic radicles. From a to b is the first internode covered by the sheath. At b is the second node, throwing out nodal roots through the sides of the sheath.

Fig. 10.-Transverse and longitudinal sections of oat sheath and plumule, near the apex; g, the rolled leaf of the plumule; its point can generally be seen green through the translucent sides of the sheath, at a short distance behind the beak of the latter. The two vascular rays h, where they issue from the embryo, are each 90 degrees from the cord 7 (fig. 13), but converge into the cord 7, where it leaves the scutellum and spreads out into the substance of the embryo.

Fig. 11.-Transverse section through maize sheath (fig. 9), and node at b on the level of an issuing root.

Fig. 12.-Transverse section of oat scutellum where the point tapers near the upper end. Wheat, barley, rye, and maize want this slender extension; 7, the cord running down the centre.

Fig. 13.-A lateral vertical section of wheat embryo through the centre; c, the point of the sheath; g, the plumule; k, the scutellum; 1, cord joining the embryo. The light parts are the primary node and embryotic roots springing out of it in the same way as roots spring out of the secondary nodes higher up the stalk.

VII. Discovery of Harpanthus Flotovianus in Scotland. By W. H. PEARSON. Communicated by Dr CARRINGTON. (Plate XV.)

(Read July 10th, 1879.)

HARPANTHUS FLOTOVIANUS, Nees.-Shoots ascending, leaves approximate, ovate-orbiculate, obtusely emarginate, horizontally arranged; stipules ovate-lanceolate, toothed on one side or entire; colesule sub-sessile, postical, cylindrical. Jungermannia Flotoviana, Nees ab Esen. in Diar. Bot. Ratib. 1833, ii. No. 26, p. 408.

Jungermannia convoluta, Hüebn. in Hepat. Germ., p. 60, No. 7 (Hep. Eur. iii. p. 570).

Jungermannia Hartmanni, Thed. Musc. Suce. exsicc., vi. No. 138, a. ferrugineus.

Pleuranthe olivacea, Taylor, in London Journal of Botany, v. p. 282 (1846) (S. O. Lindberg, Hepaticæ in Hibern. col. p. 516).

Harpanthus Flotovianus, Nees, Hep. Eur. ii. 353, 492 (1836); iii. 570 (1838); G. L. & N. Syn., Hep. p. 170 (1844); Dumortier, Hep. Eur., p. 67 (1874).

Delin.-Gottsche et Rabenh. Hep. Eur. exs. No. 417. Sullivant, Musci and Hepatica of United States, t. vii., as Pleuranthe olivacea, Taylor.

Exsice. Herb. Gunth et Beilschm, as Jungermannia viticulosa (Nees); Thed. Musc. Suec. exs. vi., No. 138, as Jungermannia Hartmanni; Gottsche et Rabenh., Hep. Eur., No. 379, and No. 417; Lindberg et Lackstrom, Hepatica Scandinavica, No. 8, et 8b.

Hab. On wet micaceous rocks, Burra Firth, Uist, Shetland Islands, June 1878, Mr John Sim.

Shoots inch to 2 inches in length. Some stems in Lindberg's "Hepatice of Scandinavia,” are quite 2 inches long; others in same collection smaller, 9 and 12 mm. The specimens in Gott. and Rab., Hep. Eur. No. 417, collected by Herr Jack, in Upper Baden (4000 ft.), are small; and those I have had the opportunity of examining collected by Mr Sim are still smaller, the largest stems. average from 7 to 8 mm., the majority only measuring from 4 to 5. These were male plants, which, as Nees mentions (Hep. Eur. ii. 358), are somewhat smaller.

Diameter of stem, 4, 5, 6 mm.

Stems (figs. 1, 2)-flexuose, procumbent, creeping amongst mosses and hepatica; mostly unbranched, but sometimes several stems issue from what appears to be the shoot of the previous year's growth. Specimens from wet stations are of a delicate green colour, more uniform in diameter, and laxly reticulate; whereas, those from drier stations are broader and of a firmer texture, and generally tinged with brown.

Rootlets (fig. 26) white, rather short, 1, 7, 6, ·5 mm.; some very short, 1 to 2 long; many have their ends swollen. One I noticed had four branches; they proceed sparingly from back of stem, generally from base of stipules.

Leaves (figs. 3-9 and 16-18), 2 × 14, 2 × 1, 1.5 × 1·5, 1.5 x 13, 15 x 1. 12 x 12, 1x1, 1x8, 9 x 6 mm. ; ovate-orbiculate, horizontally disposed; the insertion of the upper part of leaf is in a line with the side of stem,

Discovery of Harpanthus Flotovianus in Scotland. 445 whilst the base is decurrent, and brought forward by a gradual symmetrical curve. Apex contracted and emarginate; sinus small and shallow, equal to about to part of length; segments usually rounded, upper tooth sometimes larger and acute, and then overhanging the other like a claw.

Texture laxly reticulated, cells with thin walls; in young shoots, or in specimens from wet stations, we find the texture more delicate, whilst in older plants it is much firmer and thicker.

Colour.-Young shoots light green or light olive; older plants, except the extremity which is green, often with a reddish tinge. Also, as Nees mentions, some leaves are of a dark green colour. These I have noticed at the apex of some stems, where they are more or less crowded.

Stipules (figs. 10-15) large, and very distinct; ovate, ovate-lanceolate or lanceolate, acute, varying much in shape, inserted obliquely, so as to turn from the leaf opposite which they arise; some are entire, but generally they have a tooth more or less deep on the outer side about the middle; occasionally we find them toothed on both sides.

Texture and colour as leaves, size 65 × 225, 65 × 2, 6 x 2, 55 x 225, 5 × 2, 475 x 15 mm.; foreign specimens, 75 x 3, ·7 × 3, ·725 × 25, ·675 × ·275 mm.

Leaf cells (figs. 22, 23), 4, 5, and 6 sided, mostly hexagonal and longer than broad; in upper portion of leaf sub-quadrate; basal cells oblong, more regularly rhombohedral; trigones none; cell-walls thin but clearly defined; some contain a few dark green granular bodies, which usually cling to the margin of the cell. Size 0775 × 025, ·075 × 025, '06 × 03 05 ×·027, 05×03 mm.—stipular cells not differing from others.

Inflorescence dioecious.

The male plants are smaller; antheridia (fig. 21) placed singly at the base of each swollen leaf. These are elliptic or round when young, greenish with hyaline border, becoming brown when older; "very shortly stipulate" (Nees). Size 15 x 5, 1 x .1.

Colesule (fig. 24) seldom met with; it rises from the axil of a stipule, usually about half-way up the shoot, and is inserted on a very short receptacle bearing