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III. NATURAL HISTORY.

1. On Death by Insufflation, or the Passing of Air into the Lungs. -M. Leroy d'Etiolles some time since pointed out the danger of throwing air into the lungs of drowned persons, and stated that the operation, when performed simply by the mouth but strongly, was sufficient to occasion the death of certain animals, as dogs, cats, and rabbits; since then, M. Leroy has continued his experiments, and to render them more conclusive, has employed animals approximating more nearly in size to man, Seven sheep were killed in this manner; four of them died immediately, and the other three lived only a quarter of an hour. On inspecting the lungs of these animals, an unexpected result was observed; for it was found that the tearing of the pulmonary cells was not the cause of death, as had been supposed: none of the sheep who died instantly offered this appearance. In the three which died more slowly, there was certainly found a quantity of air in the thoracic cavity, but all circumstances lead to the conclusion that the accident was not the cause of their death, and that they died of asphyxia, like the others. The cause of this asphyxia has not as yet been discovered. Great difficulty occurs in examining the lesions which may have been occasioned in the lungs by the operation of throwing in air, because, according to M. Leroy d'Etiolles, nothing is more rare than to find a sheep whose lungs are unaffected by some disease, the effects of which may not be confounded with those produced by the operation. -Bul. Univ. C. x. 37,

2. Remarks on the Human Voice, by D. Liskovius of Leipsig.The remarks by M. Liskovius are in the form of a reply to objections advanced by M. Rudolphi against previous statements and opinions of the former. M. Liskovius had said that the vocal cords lengthened as the aperture of the glottis dilated. M. Rudolphi remarked upon this, that during ordinary inspiration and expiration the glottis is so much open that no sound can be heard; and, consequently, that to produce even the lowest notes of the gamut a dilatation greater than this cannot be required, as it would have no other effect than to prevent the formation of sound altogether. In reply, M. Liskovius remarks, that when in a state of repose, the larynx holds a middle place between its greatest elevation and depression, and that the glottis also is in an intermediate state between its greatest contraction and extension; the more the larynx descends, the more the glottis is dilated, and the greater the degree to which the former ascends, so much the more is the latter contracted: if, therefore, the glottis were the most dilated in a state of repose, the larynx should, at the same time, be at the maximum of depression, and its depressing and dilating muscles would be at the maximum of contraction; in such a case, each person would talk

in the lowest tones of his voice; as the state necessary to produce them would be that which would offer itself.

That ordinary respiration produces no sound, does not depend upon the too dilated state of the glottis, but upon the feeble impulse given to the column of air traversing the larynx; a point neglected by M. Rudolphi. As to the falsette, it is produced by the anterior part of the glottis, the ligaments being at such time tense and drawn together, whilst the open or pectoral voice is produced by the approximation of the open cords, without any simultaneous tension of them. M. Liskovius contends also, that the falsette is a well-characterized species of voice, and not an imperfect voice, as has been supposed by Haller, Kempelin, and Rudolphi. The conclusions drawn, and principles established, are founded upon anatomical examinations of, and experiments upon, the human body.— Archiv. für Anat. 1826, p. 116.

3. Sabulous formation in the Brain.-Dr. Bergmann, of Celle, has sent a memoir to the Royal Society of Gottingen, in which he describes twenty cases of earthy granulations occurring in the plexus choroïdes of the lateral ventricals of the brains of insane persons. The various lesions observed by the author in the brains of these patients, induces him to think that this plexus belongs to the principal organs of the animal. The earthy granulations which were found in and upon the surface of the plexus, resemble those of the pineal gland. M. Stromeyer analysed both varieties, and found their constitution similar, and of the following nature:-phosphate of lime in large quantity, phosphate of magnesia in small proportion, traces of carbonate of lime, and an animal substance of an albuminous nature. Bull. Univ. C. x. p. 128.

4. Analysis of a Ferruginous Renal Calculus, by M. Boussingault. The calculus was sent from Bogota by Dr. Roulin, to M. Boussingault; it weighed rather more than a gramme (15.4 grains), was about the size of a nut, and considerably resembled certain mineral states of iron sand: being analysed, it yielded the following constitutents:

Several other calculi of similar composition and appearance were afterwards voided by the same person.-Bull. Univ. c. x. p. 128.

5. Production and Preparation of Pearls.-For Mr. Gray's observations on the artificial production of pearls, see p. 167, vol. xix., and p. 412, vol. xx., of the first series of this Journal. M. Geiger

has made some experiments upon these substances: one object was to ascertain the probability that the Persians caused birds to swallow the pearls for the purpose of removing the crust with which their surface is sometimes covered. From the trials made with two cocks, M. Geiger thinks that the practice may be rendered useful: he thinks also that the formation of pearls is always due to the introduction of extraneous bodies into the shells of the fish; he believes that they may be made artificially, with advantage, and is told that fine pearls are made in Finland in this manner.-Bull. Univ. C. x. p. 178.

6. Peculiar Cases of the Use of Milk as Food.-A giraffe, which was sent to the King of France by the Pacha of Egypt, was observed never to drink the smallest quantity of water, but only milk. This odd circumstance is explained by the person who describes its habits and manners, as resulting from the circumstance that being taken whilst young, it was, probably, supplied with milk, which not having been discontinued, has occasioned this permanent inclination in the animal. It appears very probable, that animals which drink but little naturally, will not drink water, if a sufficient quantity of milk be supplied to them. Milk was offered to two young asses which had been separated from their dam for some time, and they drank it with pleasure. It was then offered to a young mule, and to a horse five years of age; both drank of it. Being offered to a monkey, it seemed never to have taken enough. Pigs, dogs, cats, and rats, drink milk with avidity. "I will quote on this occasion a curious fact, but little known,-that of a goat which sucked itself, and which was, with difficulty, broken of this bad habit." Now, as there are

so many animals which like milk, without having preserved the habit of drinking it, it will not seem surprising that the giraffe, a herbivorous animal, which has been continually supplied with this drink, should prefer it to all others.- Mem. du Museum, xiv. p. 74.

7. Preparations of Henbane and Belladonna, by M. Buchner.M. Buchner prefers the well-prepared extracts of these plants in practice, to the purified and peculiar principles in their crystalline forms. His process for preparing the extracts, consists in pulverising the plant, and digesting it in alcohol of a specific gravity of .847 for several hours; the liquid is then to be filtered, distilled until twothirds have passed over, and the residue evaporated until of the consistence of extract. It is then to be re-dissolved in water, filtered and re-evaporated to dryness. The extracts thus obtained are of a yellowish colour, transparent in thin plates, possessing the odour of the plant, and soluble in water and alcohol.

Dr. Reisinger, who has employed these preparations, concludes

that it is advantageous to employ the dry plants in the preparation of the extracts. 2. That the roots of henbane give a less active extract than the leaves. 3. That the seeds of this plant furnish the most active extract, and contain much malate of hyoscyama. 4. That the seeds of belladonna yield a more active narcotic extract than the leaves. 5. That the extract obtained from the roots of the belladonna is preferable to that from the leaves, but not so good as that from the seeds.-Repert. fur die Pharmacie.

8. On the Culture of Bees in Forests, by M. Buttner.-It has been a custom in Livonia, from time immemorial, to make cavities in the trees of a forest for the purpose of receiving and rearing the swarms of bees. Some of the proprietors have hundreds and even thousands of bee trees. Those which are chosen for this use are large oaks, firs, pines, alders, &c. It has been objected to this system, that it destroys the forests and diminishes the quantity of building wood, but M. Buttner observes that it is not necessary to choose the finest trunks, and that stunted trees are equally serviceable for this use, if they have sufficient size. He states also that a bee tree is worth more than if sold for wood; that the old hollow trees which will serve for an age or two, spread seed around, and cause the production of young suckers, which would be obtained with difficulty, by destroying the old trunks. He adds, that the pure air of the higher regions agrees better with the bees than the air inclosed in hives which receive the exhalations of the earth, and in which contagious diseases sometimes make great ravages. The proof he offers is, that when garden bees swarm they are directed instinctively towards the woods, whilst the bees of the wood never swarm towards the gardens.-Bull. Univ. D. vii. 34.

9. Signs of Increase, Maturity, and Decay in Trees, by M. Baudrillart. The qualities of wood depend much on the state of the tree when cut down. It appears from the experiments of M. Hartig upon wood applied as fuel, that trees which have attained maturity without passing into decay, are the best for the production of heat. Thus the value of an elm of one hundred years is to that of one of thirty years, as twelve is to nine; that of an ash of one hundred years to one of thirty years, as fifteen to eleven. When the trees begin to decay, their value rapidly diminishes; thus, if an oak of two hundred years yields wood worth fifteen rancs per corde, a tree of the same kind passing to decay yields wood only worth twelve francs. When the wood is used for other purposes, the advantages conferred by a mature but healthy state are still more considerable.

The common elm, growing in a forest and in good earth, acquires its full increase in about one hundred and fifty years, but it will live many ages, even five or six hundred years. Large forest elms are cut down with advantage when of an age between one hundred

and one hundred and thirty years, and then furnish a large quantity of building wood. The duration of the life of the elm depends much upon the soil; in a dry soil it becomes aged, as it were, in forty, fifty, or sixty years. Elms which have been lopped live for a shorter period than the others. Those which grow by the road side, or in thin plantations, may be cut when seventy or eighty years of age. In general, the increase of hard woods, as the oak and the elm, is small at first; it successively augments until the twentieth or twenty-fifth year, is then uniform until the age of sixty to eighty years, after which it sensibly diminishes.

For these and other reasons, it is important that trees should be cut down when they are at their mature state, and not simply when they undergo no further increase. When the period has arrived after which the increase of the tree would be less and less from year to year, then the tree should be felled, for no advantage accrues from its remaining longer in the ground. The indications of the mature state of a tree are by no means so evident as those of decay, but still certain signs of these states, as well as of the vigorous condition of the tree, may always be observed.

I. Signs announcing the vigour of a tree.-The branches, especially towards the top, are vigorous: the annual shoots strong and long; the leaves green, vigorous and thick, principally at the summit, and falling late in autumn; the bark is clear, fine, united, and nearly of the same colour from the foot to the large branches. If at the bottom of the veins or divisions of the thick bark there appear smaller divisions which follow from below upwards in the direction of the fibres, and live bark be observed at the bottom of these divisions, it is an indication that the tree is very vigorous and rapidly increasing in size. If some of the lower branches stifled by the others are yellow, languishing, and even dead, this is an accidental effect, and is no proof of the languor of the tree. Finally, it is a sign of vigour when branches are seen at the summit of the tree rising above and being much longer than the others; but it is to be observed that all trees with round heads do not throw out branches with equal force.

II. Signs which indicate that the tree is mature.-Generally the head of the tree is rounded; the shoots diminish in length each year, and the furthest shoots add to the length of the branches only by the length of the bud; the leaves are put forth early in spring and become yellow in autumn before those of vigorous trees, and at this time the lower leaves are greener than the upper. The branches incline towards the horizon, and form angles sometimes of sixty or seventy degrees. These apparent signs, and the thinness of the layer deposited by the sap, indicate that the tree makes but small additions to itself, and now it should be cut down. The nature of the earth should be examined, as well also as the kind of tree, to enable a judgment whether the tree should be left to in