13 seconds, he remarks that, so far back as April, 1869, he pointed out the ratio of the probable errors arising from this cause in the transits of 1874 and 1882.

In a paper on the same subject, Mr. Proctor points out that from Mr. Stone's observations upon the transit of November, 1868, it can be shown how the discrepancy of 13 seconds can be reduced to one of only the tenth of a second.

Mr. Birt describes the spots and markings on the floor of the lunar crater Plato.

The Assistant-Secretary, Mr. Williams, has just completed the translation of the Chinese records of comets observed from B.C. 613 to A.D. 1640. Some of the observations will probably bear important fruit, since no well-authenticated accounts of comets, seen so long ago, exist elsewhere.

Mr. Browning supplies a most interesting paper on a change in the colour of the equatorial belt of Jupiter. During the month of October last he noticed that this belt, which is usually the brightest part of Jupiter's disc, exhibited a strong greenish yellow colour, and was darker than the bright belts north and south of it. Other observers, using Browning's reflecting telescopes, have observed similar appearances. Indeed, it is worthy of notice that, not only these changes of colour, but the colours ordinarily present in the discs of Jupiter and Saturn have been only seen distinctly with reflectors. MM. De la Rue and Lassell, for example, have seen these colours with their fine reflectors, whereas Dawes, with all his astonishing powers of vision, and though he used refractors of exquisite defining power, has not been able to recognize them clearly, if at all. Mr. Weston supplies an interesting note on the lunar Apennine range and adjacent regions.

Mr. Carrington describes his new Observatory at Churt, Surrey. The principal telescope is an alt-azimuth, constructed on a new principle, the horizontal axis being the effective optical axis. A movable prism, placed outside the object-glass, reflects the object along the tube. Thus the telescope need never be raised, and the observer can remain always under cover.

Mr. Proctor puts forward a new theory of the Milky Way. He regards this sidereal group as forming a spiral of really small stars, swayed into its present position by the attractions of the large stars which are seen on the galaxy.

Messrs. Airy and Simms have at length brought their new eyepiece to its simplest and most perfect construction. By the mere rotation of the eye-glass-which must be plano-convex-all the effects of the flint-glass prisms described in our last Chronicle can be obtained without any mischief to the optical performance of the telescope.

Mr. Proctor supplies a paper on the application of photography

to determine the solar parallax from the transit of Venus in 1874. It is illustrated by fifteen pictures of the earth on her passage through the shadow-cone of Venus. The object of the paper is to show how photographs of the sun may be so taken, at different stations, that the relative displacement of Venus may be on a radius of the sun's disc.

In another paper he exhibits a method of constructing charts by which the great circle course between any two points on the globe may be accurately and quickly obtained.

Mr. Browning has invented a new form of micrometer for measuring the position of lines in faint spectra. By this arrangement an image of a bright cross is thrown on the spectrum, which it can be made to traverse by turning a micrometer screw. The advantages of the plan will be appreciated by those who know the difficulty of determining the position of the spectral lines by the usual arrangement.

4. BOTANY.

Influence of Climate and Soil upon Plants.-M. Kerner, of Innsbruck, has published a very interesting pamphlet on this subject, one of great importance in relation to the question of the origin of species. In the centre of distribution of a species, where it reaches its maximum of abundance, it is very unusual for varieties to become established; since, even if deviating forms were to appear, they would not be perpetuated, in consequence of the law of nature that cross-fertilization with other individuals, rather than self-fertilization, is the rule. On the outskirts, however, of the region of distribution, where the individuals are very scattered, a variation once appearing is likely to become established; because, the chances of self-fertilization being much greater, the peculiarities are likely to be perpetuated by heredity. Here therefore we must look for those aberrant forms which become the ancestors of new species. The author believes the direct influence of climate or soil in originating changes in the structure of plants to be extremely small; these changes being effected only in the course of many generations by the process of natural selection, those individuals which exhibit slight divergences suitable to the circumstances in which the plant is placed being most likely to survive, and to produce large numbers of seeds. Changed conditions of life can kill a plant, or destroy its health, but can have no direct influence in transforming it into a form more suitable for those conditions. As a contribution towards a series of observations on the relation between the flora of a country and its natural conditions of soil and climate, M. Kerner has paid special attention to the general features of the flora of the

Tyrolese Alps. Owing to the shortness of the period of activity of vegetation, which does not average more than from 1 to 3 months, few plants ripen their seeds before the return of constant frost. In consequence, while the proportion of annual plants is in the Mediterranean flora 42, and in that of the south-east of Europe 56 per cent., in the Alpine flora it is only 4 per cent. From the same circumstance the flower-buds of Alpine plants are commonly developed in the autumn before the return of frost, and burst into bloom immediately on the melting of the snow, before the appearance of the leaves. Another peculiarity of the Alpine vegetation is the very large number of plants with rosettes of stiff succulent or fleshy leaves, which both serve as reservoirs of food during the long winter, and are also proof against the sudden evaporation caused by the hot sun during the summer months. In contradistinction to this, is the almost entire absence of the bulbous plants which form so prominent a feature of the Mediterranean vegetation. Again, while the forests of tropical countries, where the summer is long and intense, abound with a luxuriance of climbing and creeping plants, these are almost entirely absent from the Alpine flora, where plants do not require to seek the shade.

Relation between the Distribution of Plants and of Animals.Professor Delpino, of Florence, traces the gradual disappearance of many classes of plants as one proceeds northwards, to the absence of those animals, chiefly insects, which are necessary to effect their fertilization. In the Tropics many plants are fertilized by the agency of humming-birds, especially those possessing large trumpetshaped flowers of a scarlet hue; and these are the first to disappear. Next follow those fertilized by the larger Lepidoptera and Coleoptera, as roses, peonies, the night-flowering Sileneæ, &c. In the Arctic zone those plants only can survive which are fertilized by Hymenoptera or Diptera, or by the wind; a few flies and midges, and a bee (Bombus terrestris) being the only insects found so far north as Nova Zembla. In the gardens near Florence are two species of Lobelia, one of which is abundantly visited by humble bees, and produces seed very freely; the other, notwithstanding its beauty and the abundance of its honey, is never visited by insects, and never bears seeds, but can easily be fertilized by artificial impregnation. Professor Delpino believes that in its native country it is fertilized by humming-birds.

Flora of Iceland.-Professor C. C. Babington read an interesting paper before the Linnean Society, January 20th, "On the Flora of Iceland." The most recent investigations have brought up the number of flowering plants indigenous to the island to about 450, of which all, with the exception of about sixty, are found also in Britain; all the remainder, with three exceptions, are natives of the European continent, chiefly of Scandinavia; there is no species of

flowering plants peculiar to the island. No woods are now to be found in the country, although some existed recently; the trees were all birch; nor is there any trace of the former existence of pines, or of any other kind of forest-tree; extensive woods of dwarf birch-trees are found in several parts, and some shrubby willows. No grain of any kind is grown on the island. The north-west corner, which has been comparatively little visited, appears to enjoy the least inhospitable climate.

Flora of Round Island, Mauritius.-At the meeting of the Linnean Society, held March 3rd, Dr. J. D. Hooker read a very interesting letter from Sir Henry Barkly, Governor of Mauritius, on the flora of this very little-known dependency of the colony. The island is about 25 miles from Port St. Louis, and only about 3 miles in circumference and 1 mile across; but its flora differs from that of the Mauritius, not only in species, but also in genera and even in families, although the depth of the intervening sea is only 400 feet. The island consists of a mound of tuff about 1000 feet in height, but without any apparent crater, bare of vegetation in the lower part. Only about twenty-four species of flowering plants were gathered during the visit, of which more than one-half are not found in the Mauritius, including three species of palm, one of them 30 or 40 feet high, a Pandanus or screw-pine, and two species of ebony. The fauna is equally peculiar.

Movements of Chlorophyll.-A very interesting series of observations has been made by the French botanists, Prillieux, Rose, and Brongniart, on the apparently spontaneous movements within the leaves of plants of the grains of chlorophyll which constitute the green colouring matter. These grains had been noticed by previous observers to congregate under the direct action of light. M. Prillieux performed his experiments on a species of moss, a kind of plant which offers great facility for these observations, as the movements can be observed in them under the microscope without dissection, owing to their transparency. When the moss had been kept in the dark for some days, the cells presented the appearance of a green network, between the meshes of which was a clear transparent ground. All the grains of chlorophyll were attached to the walls which separate the cells from one another; there were none on the upper or under walls which form the surfaces of the leaf. Under the influence of light the grains change their position from the lateral to the superficial walls, the movement taking place, under. favourable circumstances, in about a quarter of an hour. On attaining their new position, the grains do not remain entirely immovable, but continually approach and separate from one another. If again darkened, they leave their new position, and return to the lateral walls. Artificial light produces the same effect as daylight. A protoplasmic material is intimately associated with the grains of

chlorophyll, causing them to move in masses of network rather than in isolated grains; and this protoplasm is supposed to be the vital and animating part of the cell.

Climbing Plants.-M. Paul Lévy sends from Nicaragua some interesting observations on climbing plants. Their vitality is something wonderful. M. Lévy tried many experiments upon them, and found that burning was almost the only effectual way of destroying them. If the stem is cut, they put out roots from their branches, and if these roots are cut off, they are reproduced even as many as eight times. This extraordinary vitality belongs, probably, only to the climbers of tropical countries, a large number of those observed by M. Lévy belonging to the genus Bignonia. Some species of climbers show a preference for particular trees on which to climb, refusing to attach themselves to some kinds, and clinging eagerly to others, in order to reach which they may have trailed for some distance along the ground. Some trees are always entirely destitute not only of climbers, but of mosses, ferns, orchids, and other epiphytes. All the climbers observed by M. Lévy turn from left to right, none from right to left, as has been stated by other observers.

Alternation of Generation in Fungi. Some remarkable observations on this subject have recently been made by M. Gabriel Rivet. It was noticed as long since as 1806 by Sir Joseph Banks, that the proximity of the Berberry-tree appears to be a cause of the prevalence of the disease known as "rust" in the grain-crops of the neighbourhood. It has now been ascertained that one of the Fungi which produce the rust in cereals, the Puccinia graminis, and the Fungus which causes the well-known orange spots on the leaves of the Berberry, the Ecidium Berberidis, are in reality different forms of the same plant; the spores of each form will not reproduce itself, but the other form. In the commune of Genlis, department of Côte-d'Or, in France, a railway company has recently planted its embankments with Berberry-trees, and immediately afterwards the crops of wheat, rye, and barley in the neighbourhood became infested with rust. A commission being appointed to investigate the subject, reported that wherever the Berberries are found the grain-crops are more or less attacked by rust; where they do not occur the crops are free, and that the planting of a single bush of Berberry is sufficient to produce the disease where it has never appeared before.

Variegation of Leaves.-M. Edouard Morren reports some important observations on the variegation of leaves, which he attributes to a kind of disease, capable of being inoculated from one individual to another, and even to a different species. By grafting a variegated plant on another, the infection can be conveyed downwards, no doubt by the circulation of the sap, and can even be carried upwards from a variegated stock to a healthy plant grafted upon it. M. Morren states that the placing of a variegated leaf beneath the bark