suspect that Jupiter may differ from the minor planets in respects even more important than size and rapidity of rotation. Processes of such a character as to alter the appearance of a belt which exceeds the whole surface of the earth many times in extent must be due, one would suppose, to an action affecting a large proportion of the planet's mass. It would be well worth while to enquire whether the spectroscope affords any indication of the nature of those processes which are now at work upon the leading member of the planetary system.

Eclipses of the Sun and Moon.-There will be an eclipse of the moon partially visible at Greenwich on January 17. The moon will rise shortly before the termination of the real eclipse, but her face will be clouded by the earth's penumbra for some time after. A fortnight later there will be a partial eclipse of the sun not visible at Greenwich.

Measuring Star-discs.-Mr. Proctor suggests a method of measuring the discs of those stars which are liable to be occulted by the moon, which would be worth trying by those who possess powerful telescopes. He remarks that "if the image of a star is put in rapid rotation (which may be done in many ways), while the centre of rotation moves in a circle, in a period exceeding the maximum duration of luminous impressions on the retina, the appearance presented to the eye will be that of an epicycloidal coil of light whose rapidly advancing end is always on a black ground. Now, if the eye be intently fixed on this coil just before the star's occultation by the moon, it is obvious that at the instant of occultation the whole coil will vanish; but during the brief interval which the luminous impression on the retina occupies in vanishing, there will be time to notice the appearance of that end of the coil which was last formed. Now, if we suppose the rapidity of rotation such that a quarter of a revolution was made while the moon was traversing the star's disc, it is clear that along that quadrant there will be a gradual diminution of light down to evanescence at the extremity. If the star had an apparent diameter only half as large, the arc of fading light would be but half a quadrant, and so on. The observation would be rendered easier by the fact that a neighbouring part of the coil would always give the means of a ready comparison." He finds that if the star's image rotated 100 times in a second, a star ten times as far off as a Centauri, and having a real diameter as large as our sun's, would give an arc of fading light about 5510 in length.

New Method proposed for observing the Transits of Venus.-Professor Young suggests that the spectroscope should be made use of in observing the approaching transits of Venus. The plan he proposes depends upon the fact that the approach of the moon to the sun's limb, at the time of the total eclipse of August last, was rendered sensible before the time of actual contact, by the gradual obliteration of the bright lines belonging to the spectrum of the chromosphere. He considers that the approach of Venus to the sun's limb just before the transit of 1874 begins, and the retirement of Venus from the limb just after last external contact, might be rendered sensible in the same manner. There seems little doubt that every method by which the phenomena presented during a transit of Venus can possibly be observed with advantage, will be well studied by astronomers, and in good time. Every astronomer worthy the name will look anxiously and hopefully for

ward to the approach of so rare and so instructive a phenomenon; and those who have the means of influencing the success of the observations or expeditions undertaken by men of science, will spare no endeavour to secure a favourable result. Cloudy weather at a few critical stations may of course render all their exertions useless. It is, in fact, impossible for astronomers, as for other mortals, to "command success; but, judging from the past history of the science, we may feel sure that they will “deserve it."

BOTANY.

The Formation of Oil in Olives.-At the meeting of the Vienna Academy of Sciences on October 21, a memoir by Herr Harz was presented to the class on the above subject. The author thus classified his results in summarising his paper:-1. This secretion in its first formed condition does not possess the common properties of the fat-oils. 2. It is inclosed almost till its complete development in true secretion-cells, the walls of which can be made visible by re-agents. 3. These secretion-cells are not simple, but contain within themselves a number of other secretion-cells (daughtercells), which, gradually developing, are finally converted into oil, while the membrane of the mother-cells itself also changes into oil. 4. This membrane was rendered visible by treatment with Miller's salt, or still better, first with this salt, then with aniline solution, and lastly with iodised chloride of zinc, these three reagents together colouring it a beautiful deep blue.

The Classification and Nomenclature of the Species and Varieties of Ivy.— Mr. Shirley Hibberd, who is well known to our readers as a successful horticulturist, admits three species of Hedera. He proposed the following subdivisions:-1. Scandent, or climbing ivies, with green leaves; 2. Scandent, or climbing ivies, with variegated leaves; 3. Arborescent, or fruiting ivies, with green leaves; and 4. Arborescent, or fruiting ivies, with variegated leaves. "Under one or more of these four subdivisions may be placed every garden ivy known." "A very brief experience with ivies will convince the observer that every scandent form tends inevitably to the fruiting form, requiring only age and immunity from the pruning-knife to produce in due time abundance of berries. It is not, however, so generally known that every fruiting form, however arborescent, is capable of reverting to its corresponding scandent form; the mere opportunity for climbingas, for example, proximity to an old brick wall-and the roots having free range in a rich soil, tending to what may be properly termed its rejuvenescence."-Paper before Linnæan Society, November 18.

Chlorophyll and its Optical Properties was the subject of a communication to the Ashmolean Society of Oxford at a meeting on Nov. 29. It was, however, little more than a summary of Smith's, Stokes', and Ray Lankester's inquiries.

Spasmodic Movements in Leaves.-We learn from a contemporary that M. Lecocq records (Belgique Horticole) some curious movements which he has observed in the leaves of Colocasia esculenta. The motion is of a peculiar quivering kind, very unlike that of Mimosa, and is somewhat forcible.

Effects of Sunlight on Vegetation.-Experiments in reference to the effects of sunlight of different intensities in developing the chlorophyll in plants have been recently made by M. Prillieux, and have been reported by him to the French Academy of Sciences. Galignani gives the following abstract of the paper:-In former experiments sunlight was weakened by being received through water or glass shades, and the results were therefore liable to be modified by the absorption of rays. To avoid this, M. Prillieux, by means of a heliostat, caused a cone of light six mètres in length to fall into a dark room, and he then placed a series of five pots, each containing barley that had been reared in the dark, within the luminous region. No. 1 was placed at a décimètre's distance from the focus of the lens through which the solar rays were transmitted; No. 2 was placed at 16 times that distance; No. 3 was separated from the latter by a further interval of 12 décimètres; No. 4 was at 55 centimètres from this; and No. 5 stood at 57 décimètres from the focus. The experiment lasted from half-past one to half-past four P.M.; and at the end of these three hours it was found that all these little plants, except those of No. 1, had become green to very nearly the same extent; while those that had remained nearest the focus, and had therefore been exposed to the fullest sunlight, had remained as yellow and sickly as before.

The Affinities of the Hydroleaceae.-According to Mr. A. W. Bennettwho has communicated a paper on the subject to the Linnæan Society (November)—the Hydroleacea, which have been severally referred to the Convolvulaceae and Hydrophyllaceae, must be retained as a separate order, including, however, two tribes, the Hydrolea with septicidal, the Namea with loculicidal dehiscence. The tendency which exists in several species of Hydrolea to substitute for the normal bilocular a trilocular ovary, indicates, in the author's opinion, a closer affinity with the Polemoniacea than has been generally supposed. From Solanacea they differ by their two styles and straight embryo; from Scrophulariaceae, by their regular corolla, five equal stamens, and two styles. The order is essentially tropical and sub-tropical, and especially American. The genus Hydrolea, which is nearly synonymous with the sub-order Hydroleæ, ranges from Arkansas to Monte Video, with a few Asiatic and African species, to which Mr. Bennett adds two new ones, from Tropical Africa, contained in the Kew Herbarium. A Fungus Parasitic on the Coffee Plant.-A curious fungus, which has lately sprung up in Ceylon in the coffee grounds, has been examined by the Rev. M. J. Berkeley, F.R.S., who has sent a letter on the subject to the Gardener's Chronicle. It is allied to the Mucors, but is erected into a new genus by Mr. Berkeley.

The New Medal of the Royal Horticultural Society.-The Council of the Royal Horticultural Society has resolved on issuing a bronze medal, to be called the "Rare Plant Medal," and to be awarded at any of the society's meetings, for the first exhibition in this country of plants of great botanical interest.

Filling up Von Martius' Place at the French Academy.—At the meeting of the Académie des Sciences, on Nov. 22, this election took place, and several candidates presented their names. The Secret Committee, which generally practically decides these matters, gave the following as the result of its

deliberations:-In the first line, Herr Pringsheim, of Berlin; in the second line, ex æquo, and in alphabetical order, M. de Bary, of Halle; Mr. Bentham, of London; M. Goeppert, of Breslau; Professor Asa Gray, of Cambridge, Massachusetts, U.S.; Herr Nægeli, of Munich; and Signor Parlatore, of Florence. Out of 41 votes, 32 were for M. Pringsheim, 5 for Signor Parlatore, 3 for Herr Goeppert, and 1 for Dr. Asa Gray. M. Pringsheim was therefore declared elected.

Wave Diagrams of the Effects of Manures and other Influences on Plants. -At a very recent meeting of the Horticultural Society, Dr. Masters presented a series of diagrams showing in graphic form the relative degrees of vigour shown by the plants in the experimental grounds at Chiswick. The most striking results shown in the diagrams were as follows:-In almost every case the plants in the unmanured boxes were the least vigorous. The application of purely mineral manures was productive of little or no result in the case of the grasses, but was much more effective in promoting vigour in the case of the clovers. A striking contrast was exhibited in the case of almost all the twelve separate kinds of plants treated with ammonia salts, or with nitrate of soda respectively. It was shown by Dr. Masters' tables that almost invariably when the plants treated with ammonia salts manifested an increased degree of vigour, those treated with nitrate of soda showed a corresponding decrease. These contrasted fluctuations occurred at a time when the weather tables showed a high rainfall and a decreased temperature. Similar antagonistic results, but manifesting themselves at a later period, when the temperature was higher and the rainfall less, prevailed to a less extent in the boxes manured with a combination of mineral manures and nitrate of soda, and of mineral manures and ammonia respectively.

The Poison of the Tutu (Coriaria ruscifolia) is reputed to have been separated from the seeds by Mr. Skey. The investigations were carried on in Dr. Hector's laboratory in the New Zealand Institute.

Motion of Protoplasm in Anacharis.-This is the subject of a memoir by Professor Schnetzler in the Archives des Sciences for September. The author tried various physical influences, and concludes that heat and light have most to do with the matter. Heat is especially active in promoting the movement; in the case of light, the most refrangible rays have the most action. Monthly Microscopical Journal, November.

The Crystals of Logwood.-Hæmatoxylin, the colouring matter of logwood, has been found to be a very beautiful object for the polariscope microscope; according to Mr. Dancer, of Manchester, quite equal to salicin.

The Stems of the Arborescent Lycopodiacea.-In the Monthly Microscopical Journal for November, Mr. W. Carruthers continues his report on the above. He describes, and figures in a good plate, the structure of Ulodendron minus.

The Double Plate of Aulacodiscus Oreganus.-Mr. R. C. Greenleaf asserts that it can be demonstrated experimentally, that these discs are formed of two shells. He believes that many of the so-called species (even some of those described by Dr. Greville) have originated in this manner.-Proceedings of Boston Society of Nat. Hist. 1869.

Influence of the Hop on Fermentation.—If we are to believe the statements of Signor Tigri, the flowers of the hop arrest immediately the development of yeast.

The Mathematics of Plant-growth.-At one of the late meetings of the Botanical Society of Edinburgh (Nov. 11), Mr. W. Mitchell presented a curicus paper, entitled "On Equations to the curved Outline of the Leaves of Plants." He attempts to find formulæ to express the curve of the outline, and this is how he does it :-Selecting a characteristic and well-developed leaf of any plant, he carefully traces its outline when placed on cardboard or stout paper; but when both sides appear to be equally developed, one-half the outline is sufficient. On this copy all the measurements are made. The point corresponding to the base of the mid-rib of the leaf is fixed on for the pole, or origin of measurement, and from it lines are drawn to the outline, making equal angles with each other. These lines are then measured by a scale divided on the edge into tenths of an inch; and as the first line, or radius vector, is the longest, we have a descending series of terms from which to construct a formula for the curve in question.

The Microscopic Character of Pollen Grains.-Herr Luerssen describes with considerable minuteness the pollen grains in the orders Onagracea, Corylaceæ, and Cucurbitaceae. His memoir is to be found in the Jahrbuch für wissen. Botanik for 1869, and is copiously illustrated.

Eophyton explanatum.-An account of specimens of this plant found in the Lower Arenig rocks of St. David's is given (with a handsome plate) in the Geological Magazine for December. The following is the description of the species named above:-A raised, moderately convex stem, about four lines in breadth; widening, however, and becoming somewhat compresse d at the joints. The surface is ribbed, and furrowed along its whole length. At the lower joint the ribs bend outwards, evidently to form a branch. The joint is obliquely placed, widened out, and its course distinctly marked by a deep sulcus. The cortical substance is very thin, and can be removed to show the internal structure. The internal structure is made up of compressed columns, running the whole length from joint to joint, evidently of a tubular nature, and bound together by very thin tissue.

State Recognition of Dr. Hooker's Services.-Dr. Hooker has been made C.B. since our last Number was published. The following is the notice from the Gazette of November 9:-"The Queen has been graciously pleased to give orders for the appointment of Joseph Dalton Hooker, Esq., M.D., director of the Royal Botanical Gardens at Kew, to be an Ordinary Member of the Civil Division of the Third Class, or Companions of the Most Honourable Order of the Bath."

The Scarlatina Fungus.-Hallier asserts that scarlet fever is the product of a fungus which he names Tilletia scarlatinosa. We hope it will be better established than his well-known cholera-fungus. He says he has never seen such an immense number of micrococci in the blood of any other infectious disease. These are at first as small as the finest pin-point, or the most minute granular matter. They are present in far greater numbers than the blood globules themselves; both swimming free in the serum and accumulated in granular masses and groups. They both accumulate on and penetrate into the blood globules. The white corpuscles as well as the red