large and very favorable for observation. Their hollow style with large orifice is delineated, showing that an open tube extends to the cavity of the ovary. But Mr. Bennett has not been able to detect the entrance of a single pollen-tube into the ovary through this open passage, and indeed he suspects that they penetrate the tissue of the style. Observations should be made here upon the native plant; and we commend the investigation to some of our botanists who may like to try their hand at microscopic investigation. They will find it interesting to observe that wonderful phenomena, the growth and prolongation of the pollen-tubes from the anther to the stigma through a considerable distance in a straight line, with unerring certainty, as if guided by some unseen agency in the right direction. On the Absorption of Rain and Dew by the green parts of Plants; by the Rev. George Henslow. Along with Boussingault's contemporary researches, these experiments appear to settle the question against the conclusions of Duchartre, who confidently decided that foliage could not absorb water or aqueous vapor. The gardeners could never believe this, and it is now clear that leaves and other green parts may imbibe moisture and do so evidently under favorable circumstances. Note on the Genus Oudneya Brown, by Dr. Henry Trimen. The accidental discovery of Dr. Oudney's herbarium, which Brown had tucked away, has brought to light the plant upon which Robert Brown founded this genus. It proves to be the Henophyton deserti, as the authors of the Genera Plantarum had indeed surmised, though they had sought in vain for the original. A nice question in nomenclature now arises. Brown unqualifiedly calls his plant the Hesperis nitens of Viviani. Cosson and Durieu, trusting to this, and ascertaining that the plant in their hands is not Viviani's Hesperis, confidently concluded that it could not be Oudneya, and so established, upon its true characters, the genus Henonia or Henophyton. Hooker and Bentham adopt the genus, guessing that it may be Brown's Oudneya, a conclusion to which Brown's character would never lead them. For the latter, not having mature seed, makes of it an Arabideous genus, instead of a Brassicaceous. Shall the rightly characterized genus now be superseded by the imperfectly and by implication erroneously described genus, which was also confused with something else? Dr. Trimen implicitly assumes that it should. If Brown had been a botanist of less fame and less accuracy, the current name (Henophyton) would probably remain undisturbed. The question may be settled by enquiring what course the authors of the Genera Plantarum would have pursued if they had identified Brown's genus by finding his specimen. We suppose they would have adopted the older name of Oudneya; and if so, it may claim to be adopted now. A. G. 6. Floral Dissections illustrative of the typical Genera of the British Natural Orders, Lithographed by the Rev. GEORGE HENSLOW, Lecturer on Botany at St. Bartholomew's Hospital, &c. For the use of Schools and Students in Botany. London: E. Stanford. An oblong 4to, with 20 pages of letter-press and 8 plates crowded with well-chosen analyses, of rather small size, between one and two hundred on each plate. The price is not mentioned, and is probably low; the execution of the figures is fairly good, and the letter-press explaining them is also a model of condensation. The book may be recommended to students and classes in the United States. A. G. 7. Decease of Botanists.-The mortality among botanists during the first half of the year 1879 is remarkable. Among the deceased are the venerable Reichenbach, Itzigsohn, Angström, Bueck (who made the Candollean index), Wm. Schimper (the schoolmate of Agassiz and one of the first investigators of phyllotaxy, but who passed most of his life in Abysinia), Grisebach, Karl Koch, Moore of Glasnevin, besides our own Bigelow and Robbins. A. G. 8. PSYCHE: Anatomy of Amblychila cylindriformis Say, by C. F. GISSLER. This carefully prepared memoir is published in volume II of Psyche, the number for May-June, 1879. It is illustrated by one plate, well executed on stone by the author. IV. MISCELLANEOUS SCIENTIFIC INTELLIGENCE. 1. Preliminary Note on the Substances which produce the Chro mospheric Lines; by J. NORMAN LOCKYER, F.R.S.-Hitherto, when observations have been made of the lines visible in the sun's chromosphere, by means of the method introduced by Janssen and myself in 1868, the idea has been that we witness in solar storms the ejection of vapors of metallic elements with which we are familiar from the photosphere. A preliminary discussion of the vast store of observations recorded by the Italian astronomers (chief among them Professor Tacchini), Professor Young and myself, has shown me that this view is in all probability unsound. The lines observed are in almost all cases what I have elsewhere termed and described as basic lines; of these I only need for the present refer to the following: b, ascribed by Ångström and Kirchoff to iron and nickel. Ångström to magnesium and iron. 5268 by Ångström to cobalt and iron. Hence, following out the reasoning employed in my previous paper, the bright lines in the solar chromosphere are chiefly lines due to the not yet isolated bases of the so-called elements, and the solar phenomena in their totality are in all probability due to dissociation at the photospheric level, and association at higher levels. In this way the vertical currents in the solar atmosphere, both ascending and descending, intense absorption in sun-spots, their association with the faculæ, and the apparently continuous spectrum of the corona and its structure, find an easy solution. We are yet as far as ever from a demonstration of the cause of the variation in the temperature of the sun; but the excess of so-called calcium with minimum sun-spots, and excess of so-called hydrogen with maximum sun-spots follow naturally from the hypothesis, and afford indications that the temperature of the hottest region in the sun closely approximates to that of the reversing layer in stars of the type of Sirius and a Lyræ. If it be conceded that the existence of these lines in the chromosphere indicates the existence of basic molecules in the sun, it follows that as these lines are also seen generally in the spectra of two different metals in the electric arc, we must be dealing with the bases in the arc also. 2. An Arabic Scientific Journal. The first number of a Scientific Monthly Journal in Arabic, has been recently issued at Beirut, in Syria. It is published by Sh. Makarius & Company of that city. 3. Bulletino del Vulcanismo Italiano; Professor M. S. DI Rossi. Roma, 1878.A few years ago Cav. Michele Rossi determined to attempt the collection and monthly publication of facts connected with Italian Vulcanology. The experiment succeeded, and a volume of 140 pages has been issued recording all the phenomena of internal telluric dynamics observed in Italy and Sicily during 1878. A list is given of twenty-six Italian observatories where seismic observations are recorded, and whose observers are in communication with Professor di Rossi. Among minor notices we find mention of various new seismological observatories, including that of the Solfatara at Pazzuoli, and of the earthquake which was felt at Fiulmalbo, Florence, and Rocca di Papa. There are letters on the application of the microphone to seismological studies, from Professor di Rossi and Count G. Mocenigo; and the Umbrian earthquake of September, 1878, is described by Professor A. Ricci. Silvestri gives an account of the mud eruption which broke out on the sides of Etna near Paterno in December; and Palmieri continues his "Cronaca Vesuviana" to the end of September, 1878. An exact account of the time of occurrence of earthquake phenomena in any part of Italy is entered in a tabular form, and it is surprising to notice that not a day passes in Italy without some indication of endogenous dynamic action. At the end of the volume is a large diagram showing at a glance the daily distribution of earthquakes throughout Italy. But the most interesting article in the Bulletino is that on the application of the microphone to the study of subterraneous meteorology, by Professor Michele di Rossi. In 1875 Count Mocenigo, of Vicenza, made an observation which was nothing less than the fundamental fact of the microphone. He observed that electric currents indicate in a galvanometer perturbations and interruptions by means of frictions and shocks produced artificially between conductors not in perfect contact. He also observed that the same phenomena were produced by natural and unknown causes, when the apparatus had not received any artificial shock. From the account of his observations Professor di Rossi concludes that these unknown perturbations arose from microseismic oscillations of the soil. He communicated his views to Count Mocenigo, who at once commenced experimenting in the direction indicated, when the news of the invention of the microphone in America was received. Professor di Rossi then commenced a series of experiments with the microphone in the Seismic Observatory which he has established at Rocca di Papa, seventeen miles from Rome. A special microphone, consisting of a balanced pointed lever lightly touching a plate of silver, was mounted on a stone pedestal and was placed twenty meters under ground, at a distance from habitations and from roads. It was also thoroughly isolated, and shut up in a box filled with wool. The instrument was watched during some of the stillest hours of the night, and the same mysterious sounds which Count Mocenigo had recognized were heard by di Rossi, which he considers were incontestably natural and intratelluric. The microseismic sounds were speedily differentiated from other sounds, and their nature was completely confirmed by their frequent coincidence with motions of the seismograph. On one occasion, as di Rossi was listening at about half past three o'clock in the morning, the telephone connected with his subterranean microphone emitted sounds like the discharge of musketry, of such loudness that he feared they would awaken a child who slept in the same room, and he therefore disconnected the telephone. A short time afterward, toward four o'clock, a sensible shock of earthquake occurred, for which the sounds had been the microphonic preparation. The microphone was afterward transported to the observatory on Vesuvius, and it was then possible to trace the precise correspondence between the movements of the seismograph and the sounds of the microphone. The above is condensed from G. F. Rodwell, Nature, vol. xx, p. 179. In this connection it may be remarked that the sources of the seismic vibrations which become audible through the microphone may be various. Thus, they might be produced by: (1.) The explosion of bubbles made by the escaping vapors, which in the case of viscid lavas would require considerable internal pressure before rupture. (2.) The sudden production or condensation of vapors. (3.) The more general condition of stress produced in the earth's crust, resulting in more or less yielding along lines of least resis tance. The premonitory sounds heard in the microphone may with probability be referred to the first or second class. C. G. R. THE AMERICAN JOURNAL OF SCIENCE AND ARTS. [THIRD SERIES.] ART. XXVI.—The Pertinacity and Predominance of Weeds; by ASA GRAY. A WEED is defined by the dictionaries to be "Any useless or troublesome plant." "Every plant which grows in a field other than that of which the seed has been [intentionally] sown by the husbandman is a weed," says the Penny Cyclopædia, as cited in Worcester's Dictionary. The Treasury of Botany defines it as "Any plant which obtrusively occupies cultivated or dressed ground, to the exclusion or injury of some particular crop intended to be grown. Thus, even the most useful plants may become weeds if they appear out of their proper place. The term is sometimes applied to any insignificant-looking or unprofitable plants which grow profusely in a state of nature; also to any noxious or useless plant." We may for present purposes consider weeds to be plants which tend to take prevalent possession of soil used for man's purposes, irrespective of his will; and, in accordance with usage, we may restrict the term to herbs. This excludes predominant indigenous plants occupying ground in a state of nature. Such become weeds when they conspicuously intrude into cultivated fields, meadows, pastures, or the ground around dwellings. Many are unattractive, but not a few are ornamental; many are injurious, but some are truly useful. White Clover is an instance of the latter. Bur Clover (Medicago denticulata) is in California very valuable as food for cattle and sheep, and very injurious by the damage which the burs cause to wool. In the United States, and perhaps in most parts of the world, a large majority of the weeds are introduced plants, brought into the country AM. JOUR. SCI.-THIRD SERIES, VOL. XVIII.—No. 105, SEPT., 1879. |