BOTANY.

Mr. Hiern's Monograph of Ebenacea.-This essay, which, however, we have not seen, we are enabled to give an account of from Professor Asa Gray's analysis of it in "Silliman's American Journal" for July. It is written by Mr. W. P. Hiern, M.A., and is published by the Cambridge Philosophical Society (vol. xii. part i.). Professor Gray says, that "In a brief account of the economical products of the order, 18 species of Diospyros, 2 of Maba, and one of Euclea, are said to supply ebony; not to speak of other hard woods, such as box-wood and pear-tree, which are artificially died black, and used in commerce as ebony; nor of the ebony of the ancients, which, according to Bertolini, was furnished by a Leguminosa. Fourteen species of Diospyros yield edible fruits. Much the best, no doubt, is that of the Japanese D. Kaki, perhaps because it has been immemorially cultivated; the next may be our N. American Persimmon, which is said to be better fit to eat after it has suffered frost. It is hardly edible without it. Characters are assigned for distinguishing D. Virginiana from the Asiatic D. Lotus; but it is added that some specimens, of which the native country is unknown, are extremely difficult to assign with certainty. For his very full list of the numbered collections, with names assigned to the numbers, our author has earned hearty thanks. Only five genera are admitted; and one of these is a new one, of a single species, from Madagascar, Tetraclis, well marked by the valvate æstivation of the corolla. Not only are lists given of the species of each geographical region, but a complete chronological enumeration of all the published species. The treatment of the systematic part of the monograph, the Latin diagnoses and the English descriptions, and the displayed synonomy, &c., seems wholly creditable; but there is a surplus of punctuation in the diagnoses, each adjective being isolated by a comma. The fossil species are all described in an appendix, but the author disclaims responsibility for them."

Gigantic Evergreens in California.-In the "Proceedings of the Academy of Natural Science of California," Dr. Kellog says he had just returned from under the shadow of the finest evergreens that there were in Californiatrue chestnut trees, Castanea chrysophylla, from 100 to 200 feet high, 4 to 6 feet in diameter, with a clean trunk of 50 to 75 feet. Similar statements he had made times unnumbered from the Academy's first existence, and were in the "Proceedings," but seemed to be overlooked by his Eastern friends. He would also state that, on the trip, he had met with the Rhus aromatica, a shrub found in Sacramento City, on his first arrival, in 1849, and often brought to his attention since. This also had often been brought to the attention of the Academy. A Viburnum is among the Academy's collection from this part of California (Mendocino County), recently presented, besides two specimens of huckleberries, if no more.

Dr. Dawson's View as to Prototaxites.-This has been recently expressed by Dr. Dawson in the "Monthly Microscopical Journal" for August, as opposed to Mr. Carruther's doctrine. Dr. Dawson says that, in discussing affinities, he must repeat that we must bear in mind with what we have to

deal. It is not a modern plant, but a contemporary of that " prototype of gymnosperms" Aporoxylon, and similar plants of the Devonian. Further, the comparison should be not with exogens in general, or conifers in general, but with Taxinea, and especially with the more ancient types of these. Still further, it must be made with such wood partly altered by watersoakage and decay and fossilized. These necessary preliminaries to the question appear to have been altogether overlooked by Mr. Carruthers. His original determination of the probable affinities of Prototaxites, as a very elementary type of taxine-tree, was based on the habit of growth of the plant; its fibrous structure, its spirally-lined fibres, its medullary rays, its rings of growth, and its coaly bark, along with the durable character of its wood, and its mode of occurrence; and he made reference for comparison to other Devonian wocds and to fossil taxine-trees.

Activity in the Growth of Plants.—A recent number of the "Gardener's Chronicle" expresses itself on this point. It says: "How little we think of the prodigious activity manifested in the growth of plants during a few weeks. The process is gradual and noiseless; moreover it is of everyday occurrence, and hence is disregarded. How much water must be absorbed and exhaled, how much air inhaled and exhaled, how much carbon fixed, during the process? Here, by way of illustration of our remarks, are some measurements of an ordinary plant of Abies Nordmanniana, which we took a day or two since. The shrub is only 2 feet 6 inches in height, the number of young shoots of this year's growth upon it is five hundred and eightyfive (585); the shoots vary in length from half an inch to 6 inches, their aggregate length is eleven hundred and seventy-one (1,171) inches, or nearly ninety-eight (98) feet. Dividing the aggregate length of the shoots (1,171 inches) by their number (585), we find the mean length of the shoots to be about 2 inches. The average number of leaves on each inch of a number of shoots taken at random was 34, so that the total number of 'leaves on these 585 shoots may be set down at 39,814. Assuming each leaf to be only one inch in length-which is considerably under the mark, even when all the small undeveloped leaves are taken into consideration-we should have for the leaves a length of about three thousand five hundred and one (3,501) feet, so that, in round numbers, we may say that, including the shoots and leaves, the growth in length alone of this very moderate-sized young tree, during this season, has amounted to the prodigious number of three thousand six hundred (3,600) feet, so that if the shoots and the leaves could all be placed end to end in a continuous line they would occupy considerably more than half a mile!"

Death of the Chief of American Botanists.-A late number of "Silliman's American Journal" states that "John Torrey, M.D., LL.D., died at New York on the 10th of March, 1873, in the 77th year of his age. He has long been the chief of American botanists, and was at his death the oldest, with the exception of the venerable ex-president of the American Academy (Dr. Bigelow), who entered the botanical field several years earlier, but left it to gather the highest honours and more lucrative rewards of the medical profession, about the time when Dr. Torrey determined to devote his life to scientific pursuits."

A peculiar Arrangement of Wood and Bark in the Stem of Wistaria Sinensis

has been pointed out by Mr. Thomas Meehan. The vertical section showed by the annual rings of wood that it was about twelve years old. After the eighth year's circle there was a layer of bark, and over this layer two more circles of wood. On a portion of the section another layer of bark had formed between the tenth and eleventh years' circles of wood. The bark seemed to be wholly of liber, the cellular matter and external cortical-layer of the regular bark appeared to be wanting. A longitudinal section showed where these internal layers of bark extended no further upwards, and at this point there was an evident show of wood from the interior over and down this layer of inclosed bark. He remarked that this section of wood was taken from a stem which had been led to support itself in an upright position. When the Wistaria is permitted to trail along the ground, numerous rootlets are formed along its length. He thought, from the appearance of the wood in the specimen presented, that rootlets had partially formed in these erect stems, pushing through the liber; and then, instead of penetrating entirely through the bark, and forming perfect rootlets, they remained within the cellular matter, and descending joined with the regular woody layer in forming an annular course of wood. This explanation was the more plausible, he thought, from the fact that woody stems formed on the ground. Where the rootlets went quite through into the earth, the stems were nearly regularly cylindrical; but these upright stems, on which rootlets were never seen, had an irregular fluted appearance; of course, this explanation does not accord with the formation of wood in ligneous structures as generally understood; but he could not understand how the appearance presented could have occurred in any other way than as he had supposed." Proceedings of the Philadelphia Academy of Science."

The History of the Fresh-water Alga of North America.—“ Silliman's Journal " contains a short notice of Dr. Wood's recent work on this subject, which, as it is of interest, we give in full. It is now fully twenty years since the Smithsonian Institution performed an appropriate and most acceptable service by publishing the Nereis Boreali-Americana of the lamented Professor Harvey, thus enabling our students to study the marine Alga of our coasts. It proved to be one of the most popular of the Smithsonian Contributions to Knowledge. The institution has now enabled our students, and all who are curious in microscopic life, to enter upon the more difficult but not less interesting investigation of the fresh-water Algæ, by bringing out Professor Wood's important contribution. The systematic part of this goodly volume consists of 239 pages, of imperial quarto size, in which all the United States species known to the author (exclusive of Diatomacea) are arranged and described; they are illustrated by twenty-one coloured lithographic plates, which appear to be excellent. A supplement contains six species, which are described in Professor Harvey's "Nereis," which Professor Wood did not consult in season to include in their proper places; and in the preface a fine list of fresh-water species collected by Mr. Olney in Rhode Island and named a long time ago by Professor Harvey, is reprinted from Mr. Olney's "Algae Rhodiacæ." Any student of these interesting forms may thus infer how much remains to be known of them, and all should unite in thanking Professor Wood in thus opening the way to their investigation; also for the elaborate bibliography appended to the

volume. This fills thirteen pages in double columns, and is an almost exhaustive enumeration of the works and scattered papers which relate to this group of plants.

Distribution of Potassa and Soda in Plants.—In a recent number of the "Comptes Rendus," M. E. Peligot has endeavoured to determine whether a plant, watered during the entire period of its growth with water holding in solution common salt and nitrate of soda, absorbs a certain quantity of soda; and whether it takes from the soil other elements from plants of the same species cultivated under identical circumstances, but watered, some with common water and others with potassic and magnesian solutions. The tabulated observations show that the common salt and the nitrate of soda have been totally left by the plants; none of the ashes contained soda. Nitrate of soda acts only in consequence of the acid it contains, which probably combines by double decomposition with potassa or lime.

Pith of the Balsam Fir.-According to Dr. Dawson's researches, the pith of the balsam fir (Abies balsamea) has the same curious structure of pith that he years since found in Sternbergia, the pith of a Devonian conifer. It is well seen in young twigs one or two years old, and closely resembles that of Dadoxylon Materiarium of the upper coal formation of Nova Scotia. The structure is in each case an 66 organic partitioning of the pith by diaphragms of denser cells opposite the nodes."

Concealed Chlorophyll in Plants.-M. Prillieux ("Comptes Rendus," June 26th), discusses the structure of the bird's-nest orchis (Neottia nidusavis), which is generally considered a non-parasitic plant not containing chlorophyll. He observed that if a plant is placed in alcohol it turns green, and then imparts that colour to the alcohol. Under the microscope it is seen that the brown colour of the petals is due to small elongated brown bodies scattered without order through the cells and grouped round the nucleus in each cell. These bodies have the power of swelling, and are what he regards as proteinaceous analogues of crystals. The application of alkalies or acids, or even of heat, immediately turns them green, and any re-agent which dissolves chlorophyll itself in like manner becomes green. M. Prillieux ("Academy," August 1st) believes, however, that chlorophyll does not exist as such in the living plant, the most careful experiments showing no disengagement of oxygen, but rather of carbonic acid; the chlorophyll is probably rather a product of the action of the re-agents applied. The tissues contain abundance of starch, which they probably absorb in that state.

CHEMISTRY.

The direct Synthesis of Ammonia.-An interesting experimental manufacture of ammonia by mixing dry hydrogen and nitrogen, and sending the electric spark through them, has been recorded by Mr. W. F. Donkin, who has lately read a paper on the subject, which has appeared in abstract in the "Proceedings of the Royal Society." He says, that "The action of induced

electricity on mixtures of certain gases has been lately shown by Sir Benjamin Brodie (P. R. S. April 3, 1873), to yield very interesting results. An obvious application of his method was to treat a mixture of dry hydrogen and nitrogen in a similar manner as those referred to above, with the view of effecting the synthesis of ammonia; and Sir B. Brodie kindly allowed me the use of his apparatus for the purpose of the experiment, which was conducted as follows:-A mixture of about three volumes of hydrogen with one of nitrogen in a bell-jar over water, was passed through two tubes containing pumice moistened with alkaline pyrogallate and sulphuric acid respectively, then through a Siemen's induction-tube, and into a bulb containing dilute hydrochloric acid. The whole apparatus being first filled with pure hydrogen, about half a litre of the mixed gases was sent through the apparatus, the induction coil not being in action; the bulb containing the acid was then removed and another substituted, containing an equal volume of the same acid. About half a litre of the mixed gases was now passed through the apparatus, submitting them to the action of the electricity. The contents of the two bulbs were next transferred to two testtubes; and after adding excess of potash to each, Nessler's test was applied. The first solution gave a faint yellow coloration, the second a rather thick reddish-brown precipitate. No attempt was made to estimate the quantity of ammonia formed, as it would vary with many of the conditions of the experiment."

Activity of Chlorine in Darkness.-This is an interesting subject, especially as chlorine is supposed to act almost exclusively in the light. However, M. Melsens has observed that carbon in the form of coke, purified by repeated washings and ignitions in a current of dry chlorine, can absorb nearly its own weight of this gas. If now a current of hydrogen, previously dried over phosphoric oxide, be passed over this chlorinated carbon, even cold and in absolute darkness, notable quantities of hydrochloric acid gas are disengaged. A true combustion of hydrogen in chlorine takes place, the temperature being actually lowered by the return of the chlorine to the gaseous state. Vide "Comptes Rendus," lxxvi. p. 92.

Amount of Ozone absorbed by Water.-M. L. Carius has previously shown that ozone can be absorbed by water unchanged, in quantities not inconsiderable. He now finds that at a temperature of 0°, and a pressure of 0.76 m.m., 1.346 c.c. of ozone were absorbed by 100 c.c. of water; this is independent of the amount of oxygen absorbed. The ozone used in these experiments was obtained by electric action.-"Berichte der Deutschen Chemischen Gesellschaft zu Berlin," July 14.

Improvement in Photo-lithography.-In one of the numbers of the "Chemical News" for August, M. Paul gives the following description of his process: "The paper is coated with a layer of white of egg beaten up, and mixed with a concentrated solution of bichromate. When dry it leaves a hard smooth surface. After a sufficient insolation under the negative, the paper is covered with lithographic ink, then immersed in cold water to dissolve out the unchanged albumen, which is then removed with a fine sponge."

A new Deodoriser for Prevention of Epidemics.-In "Les Mondes" (August 14) M. Chodzko declares that the phenols, the hypochlorites, and