its passage through diaphanous | periment (Malus observes) presubstances composed of lamina-sents the singular phenomenon, of a body which at sometimes appears diaphanous, and at others opake, while receiving not only the same quantity of light but even the same ray of light under the same inclination. A writer in the Annales de Chimie for March 1816, p. 316 (note), probably M. Arago, observes, that most of the results announced by Dr. Brewster in his Memoir on the depolarization which light suffers, in passing through various substances of the mineral, vegetable, and animal kingdoms, are to be found in a memoir of Malus published in one of the Moniteurs of 1811, and announced in the Analyse des Travaux de la 1re classe de l'Institut pour l'Année 1811. Sir Ev. Home has also been complained of, for neglecting to cite the previous corresponding observations of the con. or subject to internal crystallization -or that by mechanical force, or by heat, may be altered as to the internal structure of their particles or that may be changed in form, as by bending into a concave and convex surface, a plane piece of glass-have the property of acting upon light in its passage through them, so as in some cases to divide, and in others to reflect the rays of the fasciculi; effects which are modified by the direction in which the rays fall on the polarizing body, perpendicularly or obliquely. These experiments have been varied by the scientific observers above mentioned in a great variety of ways, as to the kind of substances employed, the employ of one or two substances, and the different directions in which they were made to receive the rays of light. The fact first observed by Ma-tinental philosophers. This shows lus is in conformity with all the later discoveries; viz. that if a pile of glass in parallel plates be placed in the direction of a polarized ray, forming with it an angle of 35° 25', the ray produces no reflected light from any of them; hence he concluded at first, that although the light of an ordinary ray or fasciculus of rays, would have been reflected, yet in the actual case the light passed through this whole series of diaphanous bodies. But having made the incident ray to revolve on its own axis, without changing its place, it was entirely reflected by the successive action of the plates of glass, and was no longer distinguishable at the bottom of the pile; but continuing to revolve it, after it had made the revolution of half a circle, it again passed through the plates of the glass pile. This ex the necessity of early information to the scientific world, concerning the subjects about which men of science are occupied, so that we may be freed from the mortification of exclaiming, pereant qui ante nos nostra dixerunt. Mr. Brande informs us, that Dr. Brewster has lately discovered, that white light may be de composed into its complemen tary tints by simple reflection from the separating surfaces of transparent media either solid or fluid, not only that have dif ferent, but that have the same refractive and dispersive power. The experiments that led to this dis covery was placing a film of oil of cassia, and at other times of oil of cassia diluted by oil of olives, be tween two prisms or plates of flint glass; the light reflected from the first surface of the fluid film will be of an uniformly brilliant blue colour, while the transmitted light has a pale straw-yellow tint. The papers are not yet published. The French, or rather the Inventor at Paris, whose name at present I have not discovered, has introduced plano-cylindrical lenses; in which the plane surfaces are in contact, and the axes at right angles. Suppose a cylinder of glass, cut through lengthwise, and the two halves joined by their flat surfaces, but placed across each other at right angles, and then cut down to the size of the lens required. These glasses are advertised thus, Par Brevet d'Invention, conservès a surface de cylindres, Chamblant, ingenieur, opticien, breveté du roi, Rue Basseforte St. Denis No. 26 à Paris. Chamblant is not the inventor, but the contractor. This invention interferes so much with the stock on hand of the opticians, that it is with great difficulty the inventor could get workmen to grind or set his glasses. It is suspected that the influence of the Trade, has extended even to the Institute, whose committee were several years in reporting upon the merit of this invention referred to them; and I know not whether they have reported yet. I see by Thompson's Annals for this year, that they are likely to experience a similar opposition in England. It is pretended that with a larger field of vision they exhibit a perfect image of the object, in no wise distorted, without any of those coloured fringes which Dolland was at so much pains to correct; and that they are in these respects manifestly superior to the common lenses. And they are so. Some of them have been brought to Philadelphia, but the opticians will not import them, for obvious reasons. They have so much merit, VOL. I. however, that engravers, watchmakers, mineralogists, those who use spectacles, and all who require glasses of magnifying powers, will have them when they have once tried them. In telescopes they supersede Dolland's ingenious method of correcting the aberration of the rays, and no more than an eye glass and an object glass is required. The inventor (not Chamblant) in a programme on subject, has attempted to show mathematically that glasses of this construction ought from the theory to possess these points of superiority over common lenses: I have not seen the programme, but I have tried the glasses and am satisfied. the There are some observations on the superior distinctness of image afforded by concave over convex and plano-convex glasses, in Dr. Herschell's late account of his telescopic apparatus. Month. Mag. for February 1816, p. 51. BOTANY AND AGRICULTURE. On the continent of Europe, the method of Jussieu founded chiefly on the presence, number, or absence of the cotyledons of plants, bids fair to supersede the Linnæan classification. In England, I believe Brown, is the only botanist who follows Jussieu; Dr. Smith, Mr. Roscoe, and the other scientific gentlemen engaged in botanical pursuits, still adhere to the Linnæan system; which indeed is so good, and has done science so much service, that it is not likely to be thrown aside even for a better. The followers of Jussieu cannot dispense with citing the Linnæan synonimes, though the natural method of the French botanist possesses many advantages. 3 H a. Triangular: as in the laurel In France and Germany, vegeta- | has remarked in this case (etui) ble anatomy and physiology, have five different forms; of late years made more progress than in England, where Ray, Grew, and Hales, contributed largely indeed to the advancement of this branch of science, but they have not had many followers of equal repute among their own countrymen, though Mr. Knight has contributed many important facts and views. On the continent, Duhamel, La Metherie, Mirbel, Decandolles, Palissot de Beauvois, and many others, were, or still are, labouring in the same vineyard; and botany now seems likely to become a science, instead of a mere system of nomenclature: an observation which may well apply also to the present state of mineralogy. La Metherie, the respectable conductor of the Journal de Physique, a man of very extensive knowledge, and great research, but with an imagination that sometimes overruns his judgment, in his first Number, for January 1816, in giving an account of science for the year 1815, has noticed some conclusions of Palissot de Beauvois, and closed them with a brief view by himself, of the analogies between plants and animals, which I think has interest. d. The Polygon: in pines, where where the leaves are placed 2dly. The pith (moelle) is abso⚫ lutely necessary to sustain the life of the vegetable during its youth: but in old trees as in willows deprived of pith, it is supplied by medullary radiating fibres. 3dly. The monocotyledons have no pith like the dicotyledons. Yet Rumphius, Daubenton, &c. remarked in the palm tree and some other plants, a substance analogous to the pith and medullary rays. DuPetit Thouars particularly, informs us of the pandanus, the dracena, and other monocotyledons, that differed greatly in this respect from others of the same class. The gramens, the bamboos, &c. offer some still more remark Palissot de Beauvois (Jour. de Phys. Jan. 1816, p. 20) has published observations on the arrange-able exceptions in this case. ment and disposition of leaves, on the pith (moelle) of ligneous vegetables, and on the conversion of cortical layers into wood. He has drawn the following conclusions. 1st. The form of the medullary case, or envelop of the pith (etui medullaire), varies in the ligneous dicotyledons. These variations are subservient to a constant law, and depend on the arrangement either of the branches or the leaves. He 4thly. The recent woody layers are produced by the liber, and not as Hales supposed by wood precedently formed: just as in animals, the recent layers of bone are the produce of periosteum.* * M. Mirbel had long insisted that the liber changed into wood: M. Du Petit Thouars, and Mr. Knight, opposed this doctrine strenuously. M. Mirbel has come forward in article 5 of the The pith, (moelle) says the author, varies in its form and its colour. In the willow and in many other trees, the longitudinal fillets are coloured red or brown, of which we have not yet determined the use. On this, La Metherie remarks, that he first described these red vessels in the sap of the willow, l'yeble, and the hortensia, in the great work which he published on vegetation. In raising the medullary substance of a branch of the willow, La Metherie says (Considerations sur les corps organizès t. 3, p. 454) I remarked a great number of red vessels which generally formed concentric zones. They are placed in the medullary substance a quarter of a line or more from the wood; in l'yeble they are very thick. Examined with a glass, they are semitransparent and composed of small knots like the lymphatic vessels in animals. They are perfectly distinct from the trachea or air vessels. I presume they are meant to supply the circulation of the fluids in the medullary substance, like the vessels in fruits. I showed (says La Metherie) these vessels to several scavans, and to M. Palissot himself. Duhamel (in his Physique des Arbres, t. 1, p. 38) has spoken of longitudinal fibres which he observed in the pith of the willow; they assume, he says, a red colour in the old branches: but these fibres are not the red vessels of La Metherie, which are found in Bulletin de la Societè Philomathique for July 1816, and acknowledges he has been mistaken, and is now convinced of the impossibility of such a change ever taking place. the youngest branches. In the Considerations sur les etres organizès I have described (says La Metherie) with much care the different parts which form a vegetable, and I have shown that they are analagous to the different tissues or systems which Pinel, Bichat, and other physiologists have remarked in animals. I have compared the physiology of vegetables with that of animals, and all those who have observed the phenomena of living beings, have remarked the strong analogies between the organic functions of these two classes. Such were Pythagoras, his disciple Empedocles, Hippocrates, Aristotle, Theophrastus, among the ancient philosophers of Greece. Such were among the moderns Camerarius, Leuwenhoeck, Malpighi, Grew, Gesner, Perrault, Tournefort, Linnæus, Jussieu,—all these have observed the analogy between animals and vegetables and made it a ground of their researches. As the functions of animals are better known than those of vegetables, the physiology of the latter has constantly been referred to that of the former. In my Considerations sur les etres organizès, I have pursued the same course, and taken a general view of these beings, divided into fifteen classes. 1st and 2d classes, animals with bones and red blood. 3d, 4th, 5th, 6th and 7th classes, animals without bones and with white blood. 8th and 9th classes, animals without bones or sexual distinctions; agenist (from alpha privitiva, and var gigno.) 10th and 11th classes, agenişt vegetables, without known sexual marks. Cryptogamous. 12th, 13th, 14th and 15th classes, vegetables with manifest sexual organs, acotyledons, monocotyledons, dicotyledons, polycotyledons. And I have shown, continues La Metherie, 1st. That between the lowest classes of animals which are void of sexual distinction, (agenist or cryptogamous) such as the polypi, the wheel animals, &c. and the agenist or cryptogamous family of vegetables, also without marks of sexual distinction, those that form the commencement of vegetable organic being, the tremellas, the confervas, &c. there is so strong an analogy, that the line of distinction can hardly be drawn. 2dly. The organization of vegetables has also the strongest analogy with that of animals; both are formed out of, composed of cellular tissue, serous membranes, mucous membranes, and fibrous membranes of organs of respiration, nutrition, circulation, and secretion. 3dly. Vegetables, like animals, have vital powers. They have irritability, excitability,-and 'some of them, such as the valisneria, the mimosa, &c. have motions perfectly characterized. Others like the arums, have much sensible heat at the period of their flowering. These vital powers in animals and in vegetables, appear to be the effects of galvanic action which their different parts exert on each other. 4thly. Vegetables feed and are nourished like animals. We find in the one and in the other a great variety of fluids secreted by the vital action of the system. 5thly. These fluids circulate in vegetables, as they do in animals. (?) This circulation differs in animals who possess a heart, arteries, and veins, from what it is | in animals (as the agenist tribe) who have no heart. Vegetable cir culation is most similar to that which takes place in the last mentioned and lowest species of animals. 6thly. Vegetables respire; but their respiration seems most like, that of the agenist animals. 7thly. Vegetables have secretions analogous to those of animals, carried on by means of similar organs, as glandular tissues. 8thly. Vegetables produce offspring like animals; for the most part by means of sexual organs and prolific fluid. But among some vegetables, as among some animals, there is spontaneous generation. 9thly. The vegetable lives, sleeps, and dies, like the animal. (He might have said, the vegetable lives, breathes, feeds, digests, secretes, excretes, sleeps, grows old, and dies, either accidentally of disease, or naturally by rigidity of fibre, and gradually diminished excitability, like the animal.) This analogy of vegetable and animal organic functions, shows that scientifically, they may be classed as forming one family; and vegetable physiology cannot make its due progress unless by keeping in view these relations.* I have already referred to M. Mirbel's General view of vegetable nature: the following table of Humbolt is an interesting summary of the modern progress in botany. According to him, the species of plants described by the Greeks, Romans, and Arabians, scarcely |