crease still further, or whether it will be more proper to fell it. An exact age cannot be assigned for each species; but it has been observed, that an elm situated in an insulated plantation may be felled with advantage when between seventy and eighty years of age.

III. Signs of decay in a tree. When a tree becomes crowned, i.e. when the upper branches die, it infallibly indicates, especially for isolated trees, that the central wood is undergoing alteration, and the tree passing to decay. When the bark separates from the wood, or when it is divided by separations which pass across it, the tree is in a considerable state of degradation. When the bark is loaded with moss, lichen, or fungi, or is marked with black or red spots, these signs of alteration in the bark justify suspicions of alterations in the wood within. When sap is seen to flow from clefts in the bark, it is a sign that the trees will soon die. As to wounds or gutte.ngs, these defects may arise from local causes, and are not necessarily the result of old age.-Biblioth. Phys. Econom. 1826, p. 13.

10. Structure of Plants.-M. Raspael has endeavoured to ascertain what alterations are occasioned in a lengthened time by water, acids, and heat, upon feculous teguments, and, consequently, upon all vegetable tissues, which, according to him, are merely vesicles similar to the teguments. The following are some of the results which M. Raspael says he has obtained. After an ebullition continued for eighteen hours, the teguments began to appear as a layer of granules: continuing the ebullition, these granules were successively detached from each other until the liquid no longer offered traces of teguments, but merely globules from the 36th to 8th of a millemeter in diameter. These resisted ebullition during eight hours per day, for a whole month. experiment was made in vessels almost close.

The

The liquid being put into a flask half filled with air, was left; the granules required fifteen days for their precipitation, whilst the untouched feculous integuments were almost entirely precipitated on the third day, according to the quantity of fecula submitted to ebullition. The liquid part of the contents of the flask did not cease to colour iodine till a month after; the precipitated part continued to become coloured purple by iodine. Water without elevation of temperature is competent to disintegrate the globules composing feculous teguments, but requires two or three months to manifest the action.

Muriatic acid, out of contact of air, produces the same effect, but only after a month's action, provided the experiment has not been exposed to heat or light, the only difference in the experiment is, that the globules become black and charred, but still remain vesicular.

Thus M. Raspael's idea relative to the formation of vegetable cellular tissue, is supposed to be proved, the evidence being such that any one can refer to it at pleasure. The cellular tissue is composed of teguments, these of agglutinated globules, and these may be conceived to be composed of other globules, and so on to infinity.

The same phenomena being sought for in germinating grain were perfectly observed, and another analogy between the grains of fecula and many other organic grains established. M. Raspael found that the grains of fecula gradually emptied by the progress of germination were organised precisely like grains of pollen, and that pollenic granulations might be observed in their centre with perfect facility. This fact led him to study the grains of pollen particularly, and being occupied at the same time with lupuline, numerous analogies were elicited, of which the following are the principal.

The grains of pollen are composed of a vesicle, containing a variable number of other vesicles which enclose the granules that, when detached from their surface, contribute to fecundation.. Lupuline is spread over all the yellow leaves of the hop, as well as over the scaly cones of the female flower; and they are detached only as these leaves are developed. Guettard designated these grains of lupuline by the name of vesicular glands, which are found on a multitude of other vegetables.

The glands of other vegetables have the same organization, though they do not all contain the same substances. Cortical pores are merely cells, which, according to an organization identical with that of pollen and glands, contain one or two vesicles filled with granulations.

Generally, leaves which have not vesicular glands are supplied with these pretended cortical pores. Those which have no cortical pores are supplied with glands, more or less modified in their structure.

Every thing induces M. Raspael to believe that the lupuline, the glands, and the cortical pores, are destined, like the grains of pollen, to cause the fecundation of the buds; and that, in experiments on generation by means of the two sexes, it is these organs which have sometimes replaced the action of the stamens, and puzzled the sagacity of observers.—Bull. Philom. 1826, p. 155.

11. Experiments on the Fecundation of Vegetables, by M. Gaertner. In consequence of the doubts and discussions which have arisen in Germany relative to the sexual system in plants, M. Gaertner has been induced to make a multitude of experiments, for the purpose of obtaining undoubted knowledge upon this point. The experiments have been made upon four different families of plants, containing thirty species, belonging to sixteen genera: although about six hundred in number, they are still to be con

tinued. They relate-1. To the fecundation of the plant naturally or artificially, by its proper pollen: 2. To fecundation by the pollen of another plant: 3. To the action of pulverulent substances; as sublimed sulphur, pulverised charcoal, carbonate of magnesia, lycopodium, &c. and 4. To the duration and mode of action of the pollen of one plant upon the ovaria of another; principally to ascertain whether any influence would be exerted upon the form, colour, or time of maturity of fruits and seeds.

The following are a few of the facts ascertained. A microscopic quantity of the pollen proper to a plant being placed upon its pistil, has so great an influence as entirely to destroy the action of a large mass of the pollen of another plant, even though of a very near species: the proper pollen of a plant being applied by means of a pencil to the stigma, becomes so exactly attached to it, that it is difficult to remove it without injuring the stigma: with the pollen of another plant it is quite otherwise; the stigma then appropriates it with difficulty and slowly, and the difficulty increases with the difference between the species. When the fecundation of one plant is occasioned by the pollen of another, the pollen applied to the stigma disappears in a time which, all other circumstances remaining the same, varies as the affinity between the species is more or less. When once the pistil is saturated with fecundating matter, that which is afterwards applied undergoes no change either of form or colour. In natural fecundation, the stigma loses its fullness and freshness as soon as it is saturated with fecundating matter; in the cross fecundation, the stigma remains unchanged for a much longer time, and even sometimes seems to be renewed in vigour. In the latter case, the pollen which is reapplied disappears until the stigma loses its freshness. The foreign pollen retards rather than accelerates fecundation.

M. Gaertner has extended his observations much further, even to observing the changes in the corolla; on the secretion of the juices of the plant; on the period of ripening; on the different states of the seeds, &c. &c.-Bul. Univ. B. x. 77.

12. On a natural Botanical Arrangement dependant on Chemical Characters. Many naturalists have endeavoured to establish an analogy between the external forms of plants and their medicinal characters. Dr. Runge has undertaken to prove by analysis, that there is a chemical relation-1. Between the different parts of a plant (species); 2. Between the different species of a genus; 3. Between the different genera of a family. To the first point, he quotes the experiments of Vauquelin on the Hippocastan, and his own upon Belladonna and the oak; from which it results, that tannin is found in every part of the first and third, even to the cotyledons of the latter, and the narcotic principle in every part of the second. Relative to the second point, he observes that prussic acid has been found in the kernels of all the species belonging to

the genus prunus, and a yellow colouring matter in the bark of the roots of the species belonging to the genus galium. On the third point, he cites the strychnia and veratria, found by MM. Pelletier and Caventou; the first in most of the strychnos, and the second in many colchicums. The author thinks that the same principle may be applied to the different families composing any group or order.

In his experimental results, M. Runge has found that all the species of semiflosculuses, flosculuses, radiola, diphyscium, valeriana, and scabiosa, gave him one common principle, but contained in different parts, as the root, stem, leaves, &c. This substance resembles the vegetable acids which form soluble and uncrystallizable combinations with alkalies, and insoluble precipitates with metallic oxides. In the first state it has a yellow colour, but by the addition of oxygen becomes of a bluish green colour. Being combined in these two states with oxide of lead, the following results were obtained:

Having found this principle in neighbouring families, it was afterwards sought for in those which were more distant, and was found in the umbelliferous plants, the caprifolias and the plantains; but he found no trace of it in the genera campanula and rubia. On the other hand, in these he discovered a principle which he found in no other family.-Isis, 1826.

13. On the Application of a Ligature to Fruit Trees, and to Vines, by Dr. J. W. Fischer.-The process recommended by the author, is intended to be applied in place of the annular incision, which is made round fruit-trees, for the purpose of increasing the growth and the quantity of fruit. In the same place where the annular incision would otherwise be made, an iron wire is to be passed tightly round the tree two or three times, and the ends twisted together. This operation is to be performed in winter, especially in February, and before the sap is in circulation. It is unnecessary to observe, that the ligature should be applied to those branches or young trees which are to be rendered more productive. In the summer following, after the flowering, and when the fruit begins to increase in size, the ligature is to be removed, so that the wound which may have been occasioned in the bark may cicatrize. These ligatures may be repeated every year, their places being changed: they are said to produce all the good effects of ringing, and to be free from the objections which may be urged against that process. In place of iron wire, a hemp-string well soaked in oil may be used.—Bull. Univ. D. vii. 109.

14. Method of reviving Plants, Shoots, Sprigs, Slips, and other

Vegetables. This is called a proved method of reviving plants, &c.; when their leaves and buds are faded, and their bark and roots hard and nearly dry, by M. de Droste of Hülshof. The directions are to dissolve camphor to saturation in alcohol, adding the former until it remains solid at the bottom of the latter; a sufficient quantity of rain or river water is then to have the alcoholic solution added to it, in the proportion of four drops to one ounce of water. As the camphor comes in contact with the water, it will form a thin solid film, which is to be well beaten up with the water: for a short time the camphor will float in the water in small flocculi, but will ultimately combine with the fluid and disappear.

Plants which have been removed from the earth, and have suffered by a journey or otherwise, should be plunged into this camphorated water, so that they may be entirely covered: in about two, or at most three hours, the contracted leaves will expand again; the young faded and dependant shoots will erect themselves, and the dried bark will become smooth and full. That being effected, the plant is to be placed in good earth, copiously watered with rain or river water, and protected from the too powerful action of the sun, until the roots have taken good hold of the ground.

When large plants, as trees, are to be revived, their roots are to be plunged into the camphorated water for three hours; the trunk and even the head of the tree being frequently wetted with the same water, so as to retain them in a properly moistened state. But it is always best, if possible, to immerse the whole of the plant. Shoots, sprigs, slips, and roots, are to be treated in a similar manner.

If plants thus treated are not restored in four hours, their death may be considered as certain, for they cannot be recalled to life by any artificial means. They should, consequently, never be left more than four hours in the camphorated bath; because the exciting action of the camphor, when it is continued for a longer period, may injure the plants, instead of doing good to them. It is not necessary to say that the final prosperity of the plants, thus re-animated by the camphorated water, must depend upon the particular properties of the former, the state of their roots, and the pains that are taken with them. The camphor produces no other effect than to restore life to plants nearly dead: after that, all proceeds according to the ordinary laws, and their ultimate state must be left to art and nature.-Verhandl des Vereins, &c.

15. Antient Glass Bottles.-Amongst the curious and interesting objects lately discovered in the excavations at Pompeii, are five glass bottles, in some of which were olives, in an extraordinary state of preservation. These olives were soft and pasty, but entire, and had the same form with those called Spanish olives; they had a strong rancid odour, and a bitter taste, leaving a biting astringent sensation upon the tongue. A part of these olives have been analysed, and the rest have been deposited at the museum, in the same bottles in which they were found —Bul. Univ. G. vii. 142,