stomata. It is into these cavities in the cavernous parenchyma of aërial leaves that the atmospheric air penetrates when it is absorbed by the surface of the utricles of the parenchyma, that are distended with the fluids which seem to nourish the plant.

According to M. Brongniart, aquatic leaves, if submerged, differ, in being completely destitute of epidermis. It is not alone stomata that they want, as has long been known, but the epidermis also. There are none of the cavities that abound in the parenchyma of aërial leaves, but, on the contrary, the cellules of the tissue are compactly fastened together without any interstice, and the air dissolved in the water can only act on their outer surface. For this reason the proportion borne by this surface to the whole mass of the leaf is unusually great; the leaves, from want of epidermis, dry up quickly when exposed to the air, and can only exist in water or a very humid atmosphere.

Hence the author concludes that the epidermis is destined to protect aërial leaves against too rapid evaporation, and the stomata or pores of this epidermis become necessary to maintain a communication between the atmosphere and the parenchyma.

9. CRYSTALS OF OXALADE OF LIME IN PLANTS.

M. Turpin has discovered that the cellules of Cereus Peruvianus contain an immense quantity of crystals of oxalate of lime. He represents them as appearing to the naked eye like very fine glittering sand, and, under the microscope, as rectangular prisms, with tetraedral points and a square or parallelogrammic base: their size is variable; they are sometimes found collected in groups of three and four, but more commonly forming radiating spheroidal clusters, composed of crystals of various sizes. They existed in such abundance in some parts of the tissue as to form at least an 80th of the whole mass. The presence of such crystals in the tissue of plants has lately become well known to botanists, and are distinguished by the name of raphides. They may be found abundantly, in the form of needles, in the common Hyacinth, and in most succulent Monocotyledons, and in Phytolana decandria they give a kind of silvery appearance to the subcuticular tissue; but in no plants had they been previously seen so abundant or so large as in the plant which forms the subject of M. Turpin's memoir.

10. GROWTH OF VEGETABLES.

There is no subject in vegetable physiology more obscure than the manner in which plants increase in size. While botanists are at issue as to such a point as the origin of the wood and the bark of dicotyledonous trees, it is scarcely to be expected that they should agree upon the mode in which development is effected. In truth, nothing whatever certain is known upon the subject.

Lately, M. Amici, the celebrated Modenese professor, has published some observations which he hopes may throw light on the inquiry. It is well known that, in the spring, the sap of the vine exudes copiously if the plant is ever so slightly wounded, and that the discharge which, in consequence of its limpidity, is fancifully called the tears' of the vine, becomes, after a short exposure to the air, of a rusty brown. M. Amici states that he found this substance, when examined under the microscope, to consist of long interlaced filaments, which were generally simple, but sometimes subdivided into two or three bifurcations. These filaments, or tubes, consisted of numerous joints separated by diaphragms, and, while some of the cells were filled only with air, others contained little moveable granules. Upon examining the vine sap in its limpid state, it was found to be entirely destitute of any trace of organization, but it was seen that the filamentous matter made its appearance upon being exposed to the sun for six hours, twelve hours after having been collected. One of these filaments was seen to multiply its original volume 24 times in the space of ten hours, and to have at the same time given birth to two young buds. Wishing to follow the development of this vegetation still further, the same object was left eleven hours longer upon the field of the microscope; at the end of this period it had grown from 0.2375 of a millimetre in length to 2.25, and had ramified and subdivided like a tree, and presenting joints formed at intervals by diaphragms; some of these joints contained very small granules, which circulated completely in the cavity of the cellules and of the tubes. This organization is obviously that of a Conferva; but M. Amici justly remarks that its constant existence in the tears of the vine makes it improbable that it should be of such a nature; and, at all events, the fact is one highly deserving the attention of physiologists.

Figs. 1, 2, and 3 are magnified 1500 times; Fig. 4, 500 times. Fig. 1 is one variety of the filaments found in the red mucilage; it includes two joints formed by diaphragms; in the part between them are the small granules, which circulate round the whole included space as in the Chara. Fig. 2 is another variety of tube with various compartments or vacuities between the joints; these

may be false trachea. Fig. 3 is a third variety, which occurs where the vacuities are smaller; these may be the elements of porous tubes. Fig. 4 is the case, described as seen under the microscope; at first the lateral shoot extended like a bud only to the first mark; at the end of one hour it had reached the second; at the end of the second hour it had attained the third mark, and at the end of the third hour to the full extent figured, and had produced the two small buds or commencements. When the growth of the tube is seen under a high power, it appears as if it were a viscid substance pushed from within by an elastic fluid, which extends its length, but not its breadth. By degrees, molecules, or small grains appear, in the vacuities formed, and these circulate from one extremity of the canal to the other *.

11. ON CIRCULATION IN VEGETABLES.

On the 27th of September, MM. Henri Cassini and Mirbel made a report upon the vegeto-anatomical and physiological observations presented by Dr. Schultz to the Academy of Sciences. It appears that a circulation takes place in vegetables, comparable, in some respects, to that in animals. In fact, when the vessels in a portion of stem, an inch or two long and two or three lines in width, are considered, assent cannot be refused to the idea, that a vital juice exists, and that it passes several times by the same path. But there is this remarkable difference between the circulation in vegetables and in animals of a high order, that in the latter there is one point in which terminate two vascular systems very distinct from each other, one carrying the blood to the extremities of the body, the other collecting it and conducting it to its source; whilst in vegetables we discover no special point of departure, nor any double vascular system. Vessels of the same nature form a net-work, of which the meshes are so many similar circulating apparatus communicating with each other, so that there is a common motion through them whilst the parts live together, and a motion proper to each so soon as they are separated. The discovery of M. Schultz is of the highest interest for the anatomy and physiology of vegetables; it enlightens these two branches of science, the one by the other, and it proves relations to exist between animals and vegetables, which before were not even suspected to exist †.

12. NEW METHOD OF MULTIPLYING DAHLIAS.

Some dahlias belonging to M. Jacquemin having been injured by the wind in the first days of June, and some branches broken off, he placed them in the ground, in hopes of developing the flower. This did not take place; the vegetation languished, but the plants appeared good, and being carefully taken up, were found furnished

Ann. de Sciences Nat. xxi. P. 92.

Rev. Ency. xlvii. p. 784.

with tubercles. Hence a new means of multiplying these flowers, and the illustration of a curious physiological fact *.

13. SEAT OF THE SENSE OF TASTE.

The following general experiments and conclusions are from a work on the seat of this sense by MM. Guyot and Admyrauld. i. If the anterior extremity of the tongue be inclosed in a very soft, flexible case of parchment, so as to cover it completely, jelly, and in general all bodies, may be introduced into the mouth, and crushed between the teeth without any taste being distinguishable. The same effect is obtained also by retaining the tongue apart from the cheeks or teeth; sapid objects placed beyond its action give no sensation of taste. The tongue, therefore, is the essential organ of taste; the lips, palate, cheeks, and gums have no power of this kind.

ii. Nevertheless, if the tongue be entirely covered, and very sapid substances be swallowed, a little taste is perceived at the posterior part of the velum palatinum. If the palatal arch be covered with parchment, a sapid body produces its ordinary effect upon the tongue. If a little piece of extract of aloes be fixed upon the end of a rod, and passed over the palate and the roof of the mouth, it produces no other sensation than that of touching; but on the anterior and upper part of the soft palate there is a small portion of surface, not having definite limits, where the impression of sapid bodies is very sensible; the back part of the mouth does not partake in this property, so that this small portion of the palatal vault with the tongue forms the organ of taste.

iii. If the tongue be covered with parchment, pierced at the middle of its back surface, sapid bodies applied to the part produce no taste, until, being dissolved in the saliva, they gain access to the edge of the tongue. Extract of aloes passed over various parts of the tongue produce sapid impressions within a space of only one or two lines at the sides, three or four at the point, and within a curved space at the back. Hence this part of the tongue and the lateral portions are the especial organs of taste in deglutition; the portion of the soft palate already mentioned prolongs the sensation †.

14. REMARKABLE CASE OF THE RE-UNION OF A DIVIDED PART. In the Quebec Hospital Reports we find the following case :-A man in chopping wood cut off the first phalanx of the middle finger. For two hours after the accident he remained occupied at home. Although the divided portion of his finger then appeared to be deprived of vitality, it was determined to follow the plan of Balfour of Edinburgh, and to attempt to re-unite the parts. The tip of the finger was fixed to the stump by adhesive plaster, and in three days union had taken place in two or three parts; and the extremity of + Bib. Univ. 1830, p. 215.

* Jour. de Pharm. 1830. p. 760.

the finger which had been divided had as much sensation as any other part of the body. The dressing was continued, and in three more days the re-union was complete *.

15. SINGULAR EFFECT OF OPIUM.

M. Cavalier states that he had used an enema, consisting of two ounces of mucilage and a grain and a half of opium. He was seized with nausea, but no vomiting; but having removed the cover of the night-lamp, the appearance of the light produced vomiting, and this increased whenever he submitted to the action of light. He endeavours to explain this curious phenomenon, but leaves it as obscure as he found it t.

16. MECHANICAL POWERS OF A SPIDER.

The following description of the capabilities and power of a small species of spider, supposed to be the Aranea extensa, is given by the Rev. Mr. Turner, in the Transactions of the Northumberland Natural History Society: it was shown to him by Mr. Mackreth- On calling upon him (Mr. Mackreth) the next morning, he brought out a tumbler glass, which he had inverted on the table over a sprig of Laurustinus bush, on which he had observed a very small spider. Supposing that it might want air, he had slipped under the edge of the glass a small roll of paper. In less than three days, the little animal had filled the interior of the glass with minute, almost invisible threads, by means of which it had raised the sprig into the middle of the glass; and, not content with this, had raised also the coil of paper which by some accident had slipped from under the edge. After this, it laid, upon one of the upper leaves, a large ball of eggs, and having thus completed the ultimate object of its existence, it died, and fell into the meshes of its own web.

'How this little artist should have accomplished the Herculean task of raising a weight several hundred times greater than itself, and for what purpose it should have done this, are questions which may well deserve consideration.

From a comparison of the individual inquestion with the very few figured by Donovan, it appears to be most like the Aranea extensa, vol. viii. p. 48; and as it is there said to be always found upon trees, and never upon the ground, this may be the reason why it has executed the arduous task of raising the branch, on which it was confined, to the upper part of the glasst.'

17. WHITE BAIT.

Mr. Yarrell has made several attempts to preserve white bait alive, of which the following are the results:

* Baltimore Adviser. Med. Jour. 1830, p. 370. vol. i. p. 42.

Med. Surg. Jour. v. p. 335.