dead, and the proboscis lying at some distance. Fully twentyfour hours elapsed before I could examine it farther, when, to my astonishment, the proboscis was seen to contract and dilate its aperture with energy; yet the body itself had softened, and could not be lifted even on a hair pencil. Planària cornuta was discovered by Müller; but I know his animal only through the short and imperfect description given in Dr. Turton's translation of the Systema Natura, vol. iv. p. 65. There are some discrepancies between it and mine; but I think the characters in common are sufficient to show the identity of the species. Still I shall feel indebted to any one of your readers who may have access to the Zoologia Danica, if, by a comparison of the figures, he shall confirm my synonyme, or prove that it is erroneous. I am, Sir, yours, &c. GEORGE JOHNSTON, M.D. Berwick upon Tweed, Jan. 28. 1832. ART. XI. On Variations in the Cotyledons and Primordial Leaves of the Sycamore (Acer Pseudo-Plátanus L.). By the Rev. J. S. HENSLOW, A.M., King's Professor of Botany in the University of Cambridge. Sir, THE number of cotyledons in coniferous plants is well known to be very variable, and the seeds of some other dicotyledons have likewise been observed occasionally to possess more than two. The sycamore (Acer Pseudo-Plátanus L.) is a good example of this fact; and a careful search among the numerous young plants which every where spring up in the neighbourhood of this tree, has afforded me many specimens in which the cotyledons were either three or four in number. In some instances, where there were only two as usual, one of them was more or less cloven down the middle (fig. 80. a); and these served to illustrate, in a marked 80 manner, the way in which others had become possessed of more than their ordinary number. For in these cases either two of the cotyledons were not at first so large as the third, when there were three only (b); or else, when four were present, they were all proportionably smaller than in those plants which bore two 81 (fig. 81. c). This shows that the multiplication of the cotyledons in some plants may be the result merely of a subdivision in the two which belong to them in their normal condition, and that it may not have originated in any supernumerary developement of these organs themselves. Their comparative inequality, however, soon ceases as the plant developes itself. In one instance I have remarked a cohesion taking place between the two cotyledons nearly throughout their whole length (fig. 80. d), and then the young plant had strangely assumed the form of a monocotyledon. Sometimes the superfluous division was continued to the primordial leaves, of which there was one large, and two that were smaller (fig. 81. e): but I have never observed this anomaly extend beyond them; the next in succession, and all after them, being developed in pairs in the usual way. The above figures are selected from among several varieties which I possess of this anomalous germination of the sycamore. I remain, Sir, yours, &c. Cambridge, Feb. 2. 1832. J. S. HENSLOW. VERY interesting, even under ordinary circumstances, are the seedvessels, seeds, and germination of the seeds, of that free-growing, broadleaved, umbrageous tree, the sycamore. The samaras (winged capsules) are usually produced in pairs, rarely in threes; in every three which I have met with, the seed (for every capsule usually includes but a single seed) within the third samara has been imperfect. The funiculi, or umbilical cords, are to be traced with easy obviousness in their passage through the base of the samaras, and to their union with the seed's own proper envelopes. Admirable, too, is the neat and copious lining of soft and glossy down, with which the interior of the cell of the samara is coated, to lodge the seed commodiously, till winds have acted on the wings of the capsules, and disseminated them, and the moisture of the earth whereon they fall has, by its stimulus, excited the seeds they contain to germinate. "Cotyledons folded" is, in English Flora (vol. ii. p. 230.), a generic character of A'cer; in Acer Pseudo-Plátanus, the sycamore, they are circinately so, and incumbent on the radicle *: the chewed cotyledons and primordial leaves are bitter to the taste. — J. D. The earlier an error is noticed the better. Of Crambe marítima it is remarked in English Flora, vol. iii. p. 184., " Cotyledons accumbent, not ART. XII. On the Fructification of the Genus Chara. By the Rev. J. S. HENSLOW, A.M., King's Professor of Botany in the University of Cambridge. Sir, ALLOW me, through the medium of this Magazine, to state a curious fact, which I once observed in the fructification of the genus Chàra. In the Dictionnaire Classique d'Histoire Naturelle, M. A. Brongniart has noticed the difficulty of accounting for the manner in which the red matter contained in the "globule globule" (anther of Linnæus) becomes dispersed. At a certain season of the year this part of the fructification is found empty, but its outer surface does not appear to have been ruptured. It is quite contrary (as he remarks) to all analogy, for us to suppose the included matter to have passed into the "nucule" (germen of Linnæus), through the internal substance of the plant. The fact, however, to which I am about to allude, seems to show that this is nevertheless the case. At all events, I think it is well worthy of being recorded, in order that others may direct their enquiries by the additional light which it appears to me likely to throw upon this subject. A variety of the Chàra vulgàris, which grows in a running stream at Coton near Cambridge, is more highly incrusted with carbonate of lime than any specimens which I have elsewhere met with. Considerable masses of it may be dug out in the form of a loose porous stone. It was in some specimens of this variety, gathered on Nov. 3. 1830, that I met with many globules which had become white from having parted with their red matter, whilst the nucules had assumed a reddish tinge, doubtless from their having imbibed the same. Among these nucules I noticed a few in which the outer surface appeared to be spirally banded with alternate lines of red and white. (fig. 82.) The outer coat of the nucule consists of five tubes spirally twisted together, and the ends terminating in a sort of crown upon its apex. The banded appearance here described arose from some of these tubes being charged with the red matter, whilst the others were empty. Unfortunately, I could not at the time command sufficient leisure as in De Candolle's general table [Systema Regni Vegetabilis, vol. ii. p. 146.] incumbent." Examination will prove them incumbent and conduplicate, and De Candolle correct.-J. D. to examine this singular phenomenon with the minute attention which it deserved; but I made a rough sketch of the appearance, intending on some future occasion to renew my observations. I have, however, since sought in vain for fresh examples; and, as I think it possible that the appearance may have originated in some accidental obstruction in the tubes of these specimens, preventing the passage of the red matter through some of them, I wish the fact to be made known at once, in order that others may have their attention called to the subject, and not neglect an opportunity, should they chance to meet with one, of examining a phenomenon, which seems so likely to afford us further insight into the real character of the fructification of these plants. The fact which this appearance seems to me to establish is, the internal passage of the red matter from the globule to the nucule, affording us a strong point of analogy between this genus and the Conférvæ conjugatæ ; an analogy, however, which has not been overlooked in the general structure of the plants themselves. How the red matter passes from the outer coat to the inner chamber of the nucule is not so apparent; unless we may suppose it to be effected through certain minute connecting processes, detected in the fossil species of this genus, figured by Mr. Lyell in the Geological Transactions (new series, vol. ii. pl. 13. fig. 2.). I have found, upon opening some nucules which had fallen from the plant, that they were filled with perfectly smooth spherical grains of considerable size, and of a reddish tinge; and that these grains were composed of a congeries of minute granules. These grains are, probably, what some observers have imagined to be seeds, and who have in consequence described the nucule as a polyspermous capsule; whilst others, who have seen that each nucule produces only one plant, have considered these grains to be of an alimentary nature, prepared for the purpose of nourishing the young plant during the early stages of its germination. If we were to allow that any analogy exists between the Chàræ and phænogamous plants, the globule would rather seem to represent a single naked grain of pollen than an entire anther, as it has been usual to consider it: but in our present ignorance of what are the actual functions of this organ, it is perhaps safer to class this genus with the Cryptogàmia. I am, Sir, yours, &c. Cambridge, Feb. 2. 1832. J. S. HENSLOW. To the charas another very interesting consideration appertains: for within their pellucid stems, when inspected through a powerful microscope, the motion of the sap, in its course of circulation, is as obvious as the current of a river. I had the pleasure to witness this, as had several others, at the Linnæan Society's meeting on the 6th of March, 1832. Richard Horsman Solly, Esq. F.L.S., whose intimate knowledge of vegetable physiology and anatomy Professor Lindley has recently taken occasion to attest, when ascribing to a new genus in Pittospòreæ the name of Sóllya, was the gentleman who had provided this exquisite spectacle for the gratification of all who chose to inspect it; and delightful it was to see the sap, in the shape of a thousand air bubbles, dancing briskly up on one side of the chara's stem, and descending in the same lively manner on the other. The specimen inspected appeared to be an internode of a stem of Chàra, bounded by a joint at top and another at bottom: it was erect; and, I believe, in a vial filled with water, on the back of which the light of a wax candle, deprived of its glare by the interposition of Varley's dark chamber, was thrown, while the inspector viewed it from the front. Mr. Solly obligingly changed the object into various points of view, by each and all of which one remarkable fact was clearly apparent; namely, that the process of circulation was not taking place about the whole periphery of the stem or internode, but in two broad opposite lateral longitudinal bands, which effect left two also opposite lateral longitudinal bands unoccupied by any process of circulation. I find, by a communication subsequently published in the Gardener's Magazine, vol. viii. p. 143., that Mr. Burnett, of King's College, had, as early as the 17th of January, 1832, exhibited the same interesting spectacle, and apparently before the members of the Medico-Botanical Society; and from the communication cited I quote as follows: "The course of the sap in Chàra is so far ascertained, that Mr. Burnett thinks himself justified in declaring that each joint or limb has an individual circulation; and although it may have a communication with other joints, yet that its motion is complete in itself. A section of a rootlet, or of a joint, shows it to consist of two lateral, simple, semilunar ducts, each being the channel of a current that traverses the root or joint in an opposite direction to the other; the course of the one being up, the other down. These ducts, although not spiral in their structure, that is, not spiral vessels, are spiral in their disposition, being twisted as it were round a central axis, and forming two separate scale, much in the same way as the wild worm' is often scored by gardeners, who give to their scorings the term of wild worm] round the stems or branches of unfruitful trees." I may add, that, in the specimen exhibited by Mr. Solly, the spiral direction of the opposite scale or ducts was so progressive, that, although perceptible, it was not very obvious. If the spiral bands so striking on the outer coat of the nucule (fig. 82.) are but a modified continuation of the structure which obtains in the stem, the strong spiral curvature exhibited in the nucule may perhaps be accounted for by remembering the concentration of structure which plants, in their organs of fructification and reproduction, very frequently manifest.-J. D. ART. XIII. Observations made in the Neighbourhood of High Wycombe, Bucks, on the Temperature of the Atmosphere, on the Rain and the Winds, of the Months of June and July, during the last eight Years, and on the Influence of these Meteorological Phenomena on human Health. By JAMES G. TATem, Ësq., Member of the London Meteorological Society. Sir, AFTER a summer like the past, when sickness so generally and so alarmingly prevailed, it may be neither uninteresting nor unprofitable to examine into the state of the weather, as |