Abstract
PARIS Academy of Sciences, September 3.—M. Peligot in the chair.—M. Villarceau gave an outline of his and M. De Magnac's new work, entitled "Nouvelle navigation astronomique."-The following papers were also read:—On the combinations of chlor-hydrate of ammonia with the chlorides of potassium and of sodium (extract from memoir), by M. Chevreul. He was led to study these from having found in guano cubical crystals formed of chloride of sodium and chlorhydrate of ammonia; also a similar compound in a piece of sealskin taken from this guano. Some peculiarities in crystallisation are mentioned.—Considerations on the interpretation which should be given to the conditions of maxima relative to calculations of electro-magnetic forces, by M. Du Moncel (a reply to M. Raynaud).—On the discovery of a terrestrial plant in the middle part of the Silurian system, by M. De Saporta. He was shown at Caen a plate from the slatey schists of Angers, presenting evident traces of a large fern. The vegetable substance had been replaced by sulphide of iron, and much of the contour was interrupted and lacerated as if the plant had been long under water. The fern appears to rank among the Neuropterideæ; it recalls Cydopteris and Talæopleris, observed in the Upper Devonian. The Silurian system in Europe having only furnished, hitherto (of plants) algaæ, and of somewhat problematic nature, this fern may be regarded as the oldest terrestrial plant yet found on our continent; and it indicates a floral already comparatively rich and complex, therefore distant probably from the first origin of plants. M. Lesquereux has also, quite lately, found terrestrial plants in the Silurian system in America (at the base), and M. De Saporta assigns priority in this discovery to him.—Researches on the phosphoric acid of arable lands(extract from memoir), by MM. Corenwinder and Con-tamine. In forty-eight hours a saturated solution of carbonic acid sufficed to render assimilable a quantity of phosphoric acid greater than that furnished to the soil by introducing 1,000 kilogrammes of super-phosphate. The phosphates disseminated in arable land are not in the same degree soluble in water charged with carbonic acid. Their capacity depends on their molecular state and the source whence they come. The phosphates pre-existing in liquid manures are probably more attackable than others.—On the invariability of the great axes of planetary orbits, by M. Haretu. This invariability, which several geometers, and Poisson himself, believed to be quite general, exists only for the first and second powers of the masses.—On an insect destructive to phylloxera, by M. Laliman. This larva, or worm, which (the author says) might be called the cannibal of phylloxera, devours the latter most voraciously; in ten minutes he saw ninety-five disappear. He found it in the interstices or tissue of galls on the leaves of the vine.—Remarks on M. Laliman's communication, by M. Balbiani. The observation is not wholly new; the larva is that of a dipterous insect belonging to the genus Syrphus, or an allied one. All the larvce of Syrphi are aphidiphagous; their habits have been fully studied by M. Reaumur, who remarked their voracity and the indifference of taste they showed for all kinds of pucerons. M. Balbiani recommends a continuation of these researches, and cultivation of the insect.—Invasion by phylloxera of the vineyards in the environs of Vendome, by M. Prillieux. —Satellite of Mars observed at the observatory of Paris, by MM. Paul and Prosper Henry.—New stellar system in rapid proper motion, by M. Flammarion. This is perhaps still more important than the former; for it consists of two couples of stars carried along in space by the same movement of translation, and with a velocity much above the average of ordinary proper motions. The two couples are those of 17 X Cygnus and 2576 ∑. The motion is almost perpendicular to the direction of that of the sun in space.—On the wind system in the region of Lhe Algerian chotts, by M. Angot.—Study of some derivatives of ethylvinyie, by M. Nevolé.—On a mode of transmission of the disease ergot, by M. Duplessis. The ergot appeared in a part only of a field of winter wheat. The previous crop having been a weeded crop and the field having borne, before that, trefoil and vetch (plants in which ergot has not hitherto been observed), M. Duplessis infers that the ergot must have been imported by a natural vehicle; probably the waters of the Loire, which overflowed this spring, brought it from some fields further up, which were affected by the disease last year.
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Societies and Academies . Nature 16, 432 (1877). https://doi.org/10.1038/016432b0
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DOI: https://doi.org/10.1038/016432b0