Summary The trilobed caudex of Isoëtes japonica consists of two distinct structures, viz. Stem and Rhizophore, to which the leaves and roots are respectively attached; but owing to the stunted growth of the plant, all external morphological differentiation between the two organs has been completely lost. Stem.—The stem‐apex has the form of a conical mass of tissue situated at the base of the funnel‐shaped depression in the cortex. In this protuberance no definite apical cell can be distinguished. Primary xylem, phloem, and cortex are differentiated from the primary meristem of the stem. The eauline primary vascular axis is a non‐medullated monostele. Primary phloem, in which true sieve‐tubes occur, surrounds the central xylem‐core. An endophytic mycorrhiza is found in the peripheral cells of the primary cortex. The cambium, which arises very early from the outermost layer of the plerome, cuts off secondary cortex externally and secondary phloem internally. Sieve‐tubes with sieve‐areas of the typical cryptogamic type occur both in the primary and in the secondary phloem, and are continuous with those of the leaf‐traces. No secondary xylem is formed in Isoëtes japonica. Rhizophore.—The roots, the vascular bundles of which are collateral with usually endarch protoxylem, are arranged in acropetal series upon a distinct root‐bearing organ, the rhizophore, which in this genus must be regarded as an organ sui generis. The primary growth of the rhizophore proceeds from a primary meristem situated along three radiating lines which correspond to the main fissures in the caudex. The primary and secondary tissues of the rhizophore are essentially similar to the corresponding tissues of the stem. Leaf.—The protoxylem of the collateral vascular bundle is exarch in the lamina, but becomes mesarch in the sporangial region of the leaf. True sieve‐tubes occur in the phloem of the leaf. The ligule is very well developed in Isoëtes japonica. It has a protective function; the young ligule envelops the younger leaves and also secretes mucilage. Systematic.—The species of Isoëtes can be grouped together under two sections, Eu‐Isoëtes and Cephaloceraton. Isoëtes occupies an isolated position amongst recent Vascular Cryptogams, and is regarded as the sole living representative of the Class Isoëtales. In conclusion, we wish to express our thanks to Professor J. B. Earmer, F.R.S., for his valuable advice and kindly criticism throughout the course of this investigation.

With Plate XXIX and five Figures in the Text.S INCE the publication of Hooker’s elaborate monograph (8), internal features of this singular plant have already been investigated by various botanists, such as de Bary (4), Bertrand (1), Strasburger (17, 18), and Bower (2, 3). Quite recently Miss Sykes (now Mrs. Thoday) has made contributions to our previous knowledge in two papers (19, 20), in which she refers to the publications of the previous workers. It seems to me, however, that there are still some interesting anatomical features left undescribed, and also certain points requiring a thorough examination.The material of the adult leaf used for my study was dried. It was boiled in water for a short time and then soaked in spirit, and it shows the structure wonderfully well preserved. The whole leaf is 6o cm. in length and deeply cut into strips about 2 cm. in breadth. These strips are inserted on a stem io cm. in height, 17 cm. in the longer diameter, with muchbranched roots. The cotyledon and young leaf of seedlings which were raised by Mr. Hales of Chelsea Physic Garden were also examined for comparison. One of the seedlings was about three weeks old and bore two cotyledons nearly 3 cm. in length, and 5J mm. in breadth. In this stage the leaves had not yet developed, but showed themselves as small projections at the apex of the hypocotyl between the connate bases of the cotyledons. The other seedling was about seven months old, and had developed young leaves about 6 cm. long.Sections were cut by hand or microtome in three directions : transverse, horizontal (parallel to the surface of the leaf), and longitudinal (radial to the vascular bundle). Certain elements of tissue were macerated

With twenty-seven Figures in the Text I T is hardly necessary to recapitulate here the results of the previous investigators on the nature of the leaf-like organs or ' leaves' in the apparent whorls of Galium, and of many other members of the Stellatae (or Galieae, a tribe of the Rubiaceae). There is little doubt that in any whorl the two opposite ' leaves', one at any rate of which subtends an axillary shoot, are the true leaves, while the other members at the same node are stipules. Thus, in the case of a six-membered whorl there are two leaves, each of which is provided with two stipules. Where only five or four ' leaves ' occur in a whorl, it is usually understood that in the first case one, and in the second case both, pairs of stipules have undergone a concrescence. If, however, more than six ' leaves ' are present in a whorl, it is explained that one or more of the original four stipules have undergone chorisis, resulting in the production of supernumerary members. 1 Eichler found in Galium Mollugo and also Rubia tinctorum, that there are often two primordia which fuse, giving rise to a single interfoliar stipule on either side of the stem. 2 Goebcl, 3 on the other hand, found in

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NOTESDEVELOPMENT OF THE STOMA IN GNETUM GNEMON. â€" In connexion with my study of Welwitschia 1 I may here describe the development of the stoma in Gnetum Gnemon, which shows a similar type to the former plant. The structure of the stoma is very much the same as already described in Gnetum africanum . 2 Stomata are present on the under surface of the leaf, except on the veins, and are irregularly orientated. A mature epidermal cell has a sinuous outline resembling that in Tmesipteris. One of the epidermal cells becomes an initial cell which divides into two by a line usually parallel to the long axis of the cell (Fig. i). One of these cells divides again in the same way (Fig. 2). In the normal case, the