water is evaporated, the mucus is left on the skin in the form of scales. Mixed with an oily matter, it forms the epidermis; and it also enters largely into the composition of the hair and nails, and other similar parts. It is found in many of the animal secretions, but in those only which proceed from what are called the mucous membranes. One of its most useful properties is that of lubricating the different parts, and defending them from the action of chemical or mechanical stimuli. The authors mention, as a characteristic property of mucus, that it is soluble in very weak acids, by which means, it is held in solution in the urine; and, if by any cause this fluid loses its acid, the mucus is precipitated from it, and may form the basis of a calculus. This hypothesis of the origin of calculus appears to us very dubious, and incompatible with some well established facts; which would tend to indicate that an excess of acid is a more frequent cause of disease than a deficiency.

Memoir on a new Genus of the Palm. By M. LA BILLARDIERE. -The new Palm described in this paper is a native of New Ireland, an island to the N. E. of New Holland. Its greatest singularity consists in the extreme disproportion between the length and the thickness of the stem, so that it rises to the height of more than 60 feet, although it does not exceed two or three inches in diameter. From the form of its seed, M. LA BILLARDIERE has given to it the generic name of Ptychosperma; and, from its thin stem, the specific name of gracilis.

Anatomical and Physiological Observations on the Growth and Developement of Vegetables. By M. MIRBEL. The object of this paper is to explain the manner in which the different organs of vegetables are successively formed and developed; and the author therefore gives a minute account of a series of observations which he made on the kidney-bean, at the different periods of its growth. Having described the structure of the seed before it has begun to vegetate, he specifies the changes which it experiences in what he terms its first period of developement, when the little plant begins to be formed, and the cotyledons rise above the ground. A network of vessels is distributed through the substance of the cotyledons, which M. MIRBEL calls the mammary vessels; and these are sent into the radicle, which is the part that first extends itself. The fluid contained in these vessels then ascends from the radicle into the piumula, without again entering into the cotyledons. These vessels are principally of the kind which the author denominates trachea, the spiral tubes of the English botanists. Besides the vessels of this description, there are

others

others which he names porous vessels, false trachea, and mixed vessels. The first, as the name implies, have their sides pierced with a number of small apertures; the false trachea have their coats marked with clefts, as if they were composed of proper spires, but the spires are not separable from each other; and the mixed vessels exhibit all the different kinds of structure in their passage along the different parts of the plant.

The second developement of the plant takes place when it has attained the height of two or three inches above the ground. The pith of the stem is fully formed, and it is always sur rounded by a cylinder of trachea; beyond these are false trachea, and the porous and mixed vessels. Another species of vessels now come into view, which he calls beaded vessels; and which seem to be composed of the cavities of the cellular texture, lengthened out into an oval form, and communicating with each other by small apertures. The third period of developement is when all the parts of the plant are fully formed. An important change, which is now observed to have occurred, is the filling up of the trachea which are nearest to the pith; they are at first lined with a compact paste, which increases in quantity, until their coats are rendered solid through their whole extent; and they are at length quite filled up. M. MIRBEL concludes his paper by some remarks on the opinion of Hedwig, that the spires of the trachea are themselves tubular, and contain a fluid, while the central cavity contains air. He does not conceive that we have any evidence of the tubular nature of the spires; and he supposes that the central tubes may, according to circumstances, contain either fluid or air.

any

Observations on a System of the Comparative Anatomy of Vegetables, founded on the Organization of the Flower. By the Same. It is the object of this paper to ascertain whether characters exist in the internal structure of plants, by which the different genera may be distinguished from each other. The author supposed that this object might probably be accomplished by attending to the number and arrangement of the vessels which serve for the foundation and nutrition of the germen, and he accordingly made a very minute examination of these parts. He traced the vessels in their progress through every part of the flower; beginning at the foot-stalk, proceeding to the calyx, the corolla, the stamens, pistils, and lastly the germen itself. Without the aid of the plates which accompany this paper, it would be impossible to follow M. MIRBEL through all his details; and we must content ourselves with pointing out a few of the most important of his observations.

He

He discovered in the foot-stalk a difference in the distribution of the vessels in the monocotyledonous and the dicotyledonous seeds; in the former, they are in separate threads; in the latter, they completely inclose the pith. The trachea are never found except in soft parts, and such as extend themselves rapidly. No preci-e line of distinction can be drawn between the calyx and the corolla; and Linné's idea that the one is produced from the proper bark and the other from the liber seems to be without foundation, because those parts contain no trachea, while trachea are found plentifully both in the calyx and the corolla. The distribution of the vessels that go to the stamens is very various, and seems to shew that no connection exists between the situation of the stamens and the natural characters of the plant. The vessels which pass to the pistil are distributed over the ovary and the placenta; their situation and direction are very various; and M. MIRBEL has made many minute observations on this subject, which are well illustrated by the plates.

We have next some remarks on the glandular bodies which are attached to flowers: some of these appear to be composed merely of cellular substance; while others have a number of tracheæ obviously ramifying among the cells. These evidently serve for the secretion of particular fluids, and seem to be analogous to the conglomerate glands in the animal body. — On the whole, we may conclude that the investigations of M. MIRBEL are curious, and intitle him to much credit for industry and ingenuity. In the present state of botanical science, it seems scarcely possible to realize his project: but his observations, besides the immediate information which they convey, cannot fail very much to increase our knowlege of the physiology of vegetables.

An Essay on Pyrometry, or a Memoir on the different Means of determining the Degrees of Heat in the highest Temperatures, the Use to which they may be applied, the Degree of Confidence which they deserve, and the Advantages which the Pyrometer of Platina possesses, as well for Philosophical Researches as for the Purposes of the Artist. By M GUYTON DE MORVEAU.This appears to be only the first part of the author's proposed treatises on the subject, and is occupied almost entirely by a sketch of what had been previously done by others. The most valuable portion of it consists of a table in which are inserted, in corresponding columns, the results that had been obtained by former experimentalists; and they differ so much from each other as to prove the importance of the investigation, which could not be in better hands than those of M. DE MORVEAU. His own observations will form the subject of a future memoir.

MATHE

MATHEMATICS, and ASTRONOMY.

In the History of the Class, M. DELAMBRE pays some wellmerited compliments to La Place and Lagrange, for their respective solutions of a very interesting problem, relating to the stability of the solar system; or rather of the permanent magnitude of the major axis of the planetary orbits, and consequently of the mean periods of revolution. He observes that it is particularly worthy of attention that both these memoirs have been occasioned by another, not less interesting, lately read to the class by a young geometer, (Poisson,) their worthy pupil; who, in the very first steps of his career, has placed himself in the rank of the most distinguished masters.

The acceleration of the moon, although it had been proved to be restrained within limits, after which it will experience a similar retardation, made it suspected that the same fact might have place with regard to the earth and the other planets: whereas astronomers had always conducted their calculations on the supposition of its uniformity. This problem, therefore, viz. to ascertain whether or not the earth was subject to any such acceleration, became one of great importance in the present advanced state of astronomical science; and La Place had accordingly occupied himself some years ago on this subject, and had indeed demonstrated approximatively the permanent magnitude of the major axis: but, having, for the sake of simplifying the calculation, employed only the first powers of the masses, and the third of the excentricities and inclinations, some doubt still remained as to the rejected quantities. This circumstance gave rise to a memoir by Lagrange, which was published in the memoirs of the Berlin Academy, in which he proved the same as La Place, retaining all the successive powers of the two latter quantities, but still employing only the first powers of the masses. In this state, the problem remained till Poisson demonstrated the same, including the second power of the masses. Some ideas thrown out by the author of this paper (of which he did not, as it frequently happens, see the full advantage,) again drew the attention both of Lagrange and La Place to the same problem; both of whom succeeded in giving it a full and complete demonstration, but on principles totally different from each other, and by which the stability of the solar system under the present order of things is placed beyond every possible doubt.

The above is the only subject introduced into the History, under the head of mathematical discovery. The writer then passes in review a few new works published in the course of the year; beginning with the new edition of Lagrange's tract on the solutions of numerical equations; and remarking some

of

of its additions, particularly a note in which the author has shewn the application of his method to Gauss's problems relating to the solution of binomial equations having prime indexes of the form 2m+1. We shall avail ourselves of this opportunity to offer a few observations on the nature of this work, which seems to be much misunderstood in England. It is commonly thought to offer an infallible practical method for the solution of numerical equations, which, though admitted to be long and tedious, may (it is supposed) still be employed for that purpose; whereas we much question whether, since its first publication, a single equation higher than a cubic has ever been solved by it. In fact, it can only be viewed as a very ingenious and elegant theory of numerical equations, but which at the same time furnishes no practical solution of those of high dimensions. When we consider that it requires us, first, to find the equation of differences, which

rises to the degree m (m-1,), that of the original equation

1. 2

being m, and afterward to obtain the limits of the roots of this new equation, before we begin to enter on the solution of the one proposed; that we have then to find the nearest integral root of each new resulting equation, for every new figure obtained in our approximation;-after which, the continued fraction is to be converted into a series of converging fractions, and these again into decimals, and that the same is to be repeated for each of the possible roots of the proposed equation; when, we say, these processes are properly appreciated, it will not be denied that, though Lagrange's method offers a rule for the general solution of numerical equations, it must be regarded as merely theoretical, and not as supplying any practical solution of the higher equations.

M. DELAMBRE next gives a short notice of the third edition. of La Place's Exposition of the System of the World, and the second edition of Legendre's Theory of Numbers; and, lastly, an account at some length of the Exposé des resultats des grandes opérations Géodesiques, faites en France et Espagne, par MM. Biot et Arago. Nothing very particular occurs in this report, except the astonishing coincidence of the measured arc, or that which was obtained from the geodetic operations, with the same as deduced from astronomical observation; the latter giving 1374439.13 and the former 1374438.72 metres, being a difference of only 0.41 metres, or about half a yard in an arc comprehending nearly 14 degrees of latitude. It may not, however, be amiss to observe that this coincidence arises from assuming a compression of as deduced

16

from