M. Van Horen finds that two only, the L. polyrrhiza and gibba, produce leaves of a different form in winter; while with the three other species, L. minor, trisulca, and arrhiza, the ordinary leaves live through the winter, remaining on the surface. In L. polyrrhiza these winter-leaves first make their appearance in August or September. They are much smaller than the ordinary leaves, reniform or sometimes elliptical, olive-brown on both sides, and not gibbous beneath; their roots are exceedingly minute, and at first hidden within the leaf. The aëriferous cells which serve to support the ordinary leaves on the surface do not exist, causing the winterleaves to resemble an undeveloped bud. In consequence of the absence of these vessels they are heavier than the water, and fall to the bottom as soon as any agitation of the water detaches them from the parent-leaf, which perishes with the first frost. At the ordinary period of the revival of vegetation, a small bubble of oxygen appears on the upper surface of these submerged leaves, which carries them to the surface, from which they again descend should the temperature fall below a certain point. In Lemna gibba, leaves of a similar character, were observed hibernating beneath the water, differing in shape, size, and structure from those developed during the summer.

Evaporation of Water and Decomposition of Carbonic Acid by Plants. An interesting and important series of experiments has been made by M. P. P. Dehérain, of Paris, for the purpose of determining the natural agents most efficacious in promoting the physiological functions of the leaves of plants, the evaporation of water, and the decomposition of carbonic acid. The results arrived at are as follows:-1. These two processes are carried on simultaneously and with corresponding intensity, the same agents which facilitate the one being operative also with the other. They proceed more rapidly from the upper smooth and hard surface of the leaves. than from the under-surface. 2. The principal agent in determining these changes is not temperature, but light. While the amount of water given off was hardly affected by any changes of temperature, proceeding almost with equal rapidity even when surrounded by ice; in bright sunshine leaves were found to give off, in long exposure, more than their own weight of water, while in diffused light it amounted to only six to eighteen per cent., and in total darkness was scarcely perceptible. The evaporation and condensation of water proceeded with equal rapidity when the air was perfectly saturated with moisture. 3. The different rays of light are not equally efficacious in promoting these actions. M. Dehérain found, as the result of a number of experiments, that, with an equal intensity of light, the red and yellow rays, which have little photographic power, cause in the same time the decomposition of about five times as much carbonic acid, and the evaporation

of a corresponding amount of water, as compared with the action of the blue or violet rays, which are the most active in decomposing chloride of silver.

Viridescence of Leaves.-M. Prillieux has, on the other hand, shown, by a series of experiments on barley, that the production of the green colouring matter of leaves proceeds more rapidly in diffused light than in the direct light of the sun, in opposition to the production of oxygen, which is the more abundant the stronger the light.

Peloria in Labiata.-M. J. Peyritsch has presented to the Academy of Sciences at Vienna some remarkable instances of "Peloria," that is, of abnormal regularity in flowers usually irregular, observed in the order Labiata. They occur in Stachys sylvatica, the common woundwort; Betonica officinalis, the common betony; and in seventy individuals of Galeobdolon luteum, the yellow dead-nettle. In the latter instance the flowers are formed by the increase of two segments of the calyx, and by an alteration in the form of the divisions of the upper lip of the corolla, so that they become similar to the lateral lobes of the lower lip. The stamens are perfectly normal, and bear well-developed pollen; but the carpels are abortive.

The Leaves of Conifers.-At the meeting of the American Association for the Advancement of Science, held at Chicago, Mr. Thos. Meehan read a paper on the leaves of Coniferæ. He pointed out that the true leaves of Pinus consist of bud-scales; and what are popularly known as the leaves are in reality arrested phylloid shoots. The chief portion of the true leaves in most plants belonging to this order is adnate to the stem; sometimes they have the power of developing only into scale-points; sometimes into foliose tips. In Larix the true leaves are linear, spathulate, entirely adnate to the stem. There are two kinds of stem-growth. In one case the axis elongates and forms shoots; in the other, axile development is arrested and spurs are formed. On the elongated shoots the leaves are scattered; on the spurs they are arranged in whorls. There are therefore in the larch two forms of leaves: the one free, the other adnate. In Cryptomeria the true leaves adhere for four-fifths of their length on vigorous shoots; in Juniperus, for nearly their whole length on vigorous shoots; while on weaker branches they are almost entirely free. In Pinus the phylloid shoots are situated in the axils of the true leaves. Mr. Meehan sums up his observations as follows:-The true leaves of Coniferæ are usually adnate to the branches. Adnation is in proportion to the vigour of the genus or species; or of the individuals in the same species; or of the branches in the same individual. Many so-called distinct species of Coniferæ are probably only varieties of the same species in various states of adnation.

Scorching of Leaves by the Wind.-M. Marchand, engineer of Fécamp, in Normandy, has made some observations on the effect produced on the leaves of various trees by the violent storm of the 12th to the 16th of November. The wind was from the north-west; and on that side the leaves of nearly all the trees growing near the coast, except the bay, ivy, and tree-mallow, were scorched as if by fire, and lost about 39 per cent. of their normal weight; and were found to have absorbed an appreciable amount of sea-salt, which no doubt obstructed the circulation of the sap and caused them to shrivel up. The leaves exposed to the south-east were not similarly affected.

Japanese Sea-weeds. At a recent meeting of the Royal Academy of Amsterdam, a collection was exhibited to illustrate the care taken by the Japanese in applying to beneficial purposes the natural products of their country. The collection consisted of sixteen species of Algae which are useful for food or other purposes, together with fabrics manufactured from some of them. Several of the species were altogether new; in other instances the application was entirely novel.

5. CHEMISTRY.

MR. J. ALFRED WANKLYN has made known a very unexpected fact. He says that when chlorine gas is passed over metallic sodium-even when the metal is fused, and whilst in a state of fusion, shaken in contact with the gas so as to expose fresh metallic surface-there is no increase in weight, and of course no action.

The increasing demand for albumen, especially for the use of calico-printing, has at various times led to attempts to obtain a supply of this article from the blood of slaughtered oxen and sheep. M. Dolfus-Galline describes a process invented by him, and actually in operation on a large scale at the abattoirs of Dornach, France. The process is based upon the fact of the coagulation of the cruorine of the blood, and its separation from the serum, the latter yielding, by cautious management, a dried albumen, which can be applied instead of egg albumen for clear and bright colours. Ten litres of serum yield 1 kilo. of dry colourless albumen; the blood of two and a half oxen, ten sheep, or seventeen calves, produces the same quantity of dry albumen, viz. 1 kilo.

Referring to Professor Graham's researches on the occlusion of hydrogen by palladium, M. Favre states, that according to his experiments the hydrogen in palladium saturated therewith is present as a chemical compound, and not simply in the state of

condensed gas. He also states that the vapour of boiling mercury is as little a conductor of electricity as hydrogen is, and that therefore the non-conductibility of hydrogen for electricity cannot be regarded as an objection to its being a metal.

M. Chevrier has studied the action of vapour of sulphur on various gases. With oxygen it forms a slightly explosive mixture under some conditions; but usually the vapour of sulphur burns off quietly. With hydrogen it yields sulphuretted hydrogen gas very abundantly. With nitrogen the author found no action. With proto- and bin-oxide of nitrogen it forms sulphurous acid; nitrogen is set free, and if a frigorific mixture be applied to the apparatus containing the mixed gases and vapours, large so-called leadchamber crystals are obtained. Oxide of carbon yields, with vapour of sulphur, oxysulphide of carbon.

When sodium is thrown upon water, the hydrogen does not kindle, as is well known, unless the water be warmed, or the metal confined to one spot by blotting-paper. Mr. T. Bloxam, lecturer on Chemical and Natural Philosophy, Cheltenham College, has, however, found that if sodium be dropped upon nitric acid of specific gravity 1.36 (ordinary commercial), the hydrogen burns with ease; but if the acid be diluted, this result ceases. The hydrogen ceases to kindle when the acid is diluted to specific gravity 1.056. The residue contains a fair amount of ammonia.

Dr. Emmerling has been carrying on experiments on the action of water on glass and porcelain. The leading features of his results are the following:-The action of boiling liquids upon glass vessels is proportionate to the duration of time of boiling; it is proportionate to the surface which is in contact with the boiling fluid; it is independent of the quantity of fluid which evaporates during a given time; it decreases with the decrease of temperature of the solution; alkalies, even in dilute solutions, attack glass very strongly; acids, excepting sulphuric acid, generally act less than pure water. Among the salts, those act most energetically whose acids produce insoluble salts with lime, e.g. sulphate and phosphate of soda, carbonate of soda, and oxalate of ammonia, the action of each of which increases with the degree of concentration of the solution; those salts which form in water, readily soluble lime-salts, act less strongly than pure water alone, and with the greater degree of concentration of these salts the action decreases; Bohemian glass stands acids better than glass containing soda; Berlin porcelain is only perceptibly acted upon by alkalies.

Dr. H. Schwartz has observed that when the pulverulent metallic zinc which is deposited in the tubes of the Belgian zine smelting-furnaces is mixed with amorphous phosphorus in powder, and this mixture is gently heated in a hard glass combustion-tube,

while at the same time a current of dry hydrogen gas is passed through, phosphide of zinc is formed. From the phosphide of zinc so obtained, phosphuretted hydrogen may be readily prepared by means of dilute sulphuric acid, or by boiling with caustic potash.

A method of strengthening and rendering woven tissues impermeable to water has been invented by M. Newman. A sulphuric acid bath is made containing acid of about 16 specific gravity, and kept at a temperature of 57°. The woven tissues, cotton or linen, are rapidly passed through this bath, being only left in contact with the acid for from ten seconds to two minutes, according to the nature of the tissue, which is immediately after passed through very cold water, and next submitted to a thorough washing process. The effect of the action of the acid is the formation of a varnish-like matter, which, especially after it has been regularly spread over the fabric and incorporated therewith by hot-pressing and calendering, greatly increases the strength of the fabric, and renders it simultaneously impervious to water.

The manufacture of oxygen gas on a commercial scale is increasing in Paris; Mr. Fowler, who has described one of the factories, says that 500 pounds of manganate of soda, furnish 21 cubic yards of oxygen every hour. This charge is placed in a retort and superheated, steam passed over it; in five minutes all the oxygen is extracted from this quantity of the salt. Hot air passed over this residue for five more minutes restores all the oxygen given up, and the result of an hour's continuous work, or six extractions of oxygen and six re-oxidations, is 2 cubic yards of oxygen. This oxygen, when it issues from the gasometers, contains about 15 per cent. of nitrogen, but by letting the first portions escape, the quantity of this mixture can be reduced to 2 per cent. M. Tessie du Mothay affirms that one ton of manganate of soda will yield 100 cubic yards of oxygen daily, or more than 36,000 per year; and this without having to renew the salt once.

According to M. Kessler, when burning magnesium wire is placed in a vessel containing carbonic acid, the latter is decomposed, and carbon deposited. Some nitric acid should be poured into the vessel at the end of the reaction in order to dissolve the magnesia resulting from the combustion, and to make the deposit of carbon distinct. Water having been poured in a rather wide-mouthed flask, it is made to boil as briskly as possible; when, after this boiling has been continued for some time, previously-ignited magnesium wire is held deep down in the mouth of the flask, it continues to burn. The same metal burns with great brilliancy in nitrous and nitric oxide, also in sulphuretted hydrogen and sulphurous acid, but is extinguished by carbonic oxide.

Dr. Poselger deserves the thanks of the public for his determin