344 



NATURE 



\Aug, 17, 1876 



SOCIETIES AND ACADEMIES 

 Geneva 



Physical and Natural History Society, March 2. — M. 

 Casimir de Candolle gave the result of his researches on the 

 movements of the leaves of Diont^a muscipula, undertaken for 

 the purpose of ascertaining if the anatomical constitution of these 

 leaves furnished a sufficient explanation of these movements. 

 His investigation has confirmed this hypothesis and has proved to 

 him that the movements referred to, as well as those of the sensi- 

 tive, for instance, are the result of the turgescence of the tissues 

 and not of electric currents or other causes. The leaf of Dionaea 

 is composed of two essential parts ; one part petiolary, and at 

 the extremity of that a limb or circular leaf, whose two halves 

 are movable around the central nerve. Each of these two valves 

 carries three hairs, which it is sufficient to touch very gently, with 

 a human hair for example, to cause the valves to close. Having 

 investigated the internal structure of these valves, M. de Candolle 

 has found that they are composed of two different kinds of 

 tissues. The upper layer is composed of parenchymatous cells, 

 relatively young and yet turgescent ; the inferior layer of cells 

 much older, which are no longer turgescent. At a given moment, 

 and in consequence of the shock communicated to the upper 

 layer, the water which it contained is expelled, a contraction 

 is produced, and the leaf closes. All the arrangements of the 

 leaf and especially that of the secondary nerves, which are per- 

 pendicular to the great nerve, contribute to bring about this 

 niaximura movement. The gradual development ofthese leaves 

 is in favour of this theory ; the valves of all the young leaves are 

 at first rolled up and they are stretched out at the moment of 

 complete expansion. The leaf does not close if one simply 

 touches the leaf ; it is necessary to touch one of the hairs. Their 

 anatomical structure was then examined and M. de Caiidolle 

 found that they are composed of very elongated cells, forming a 

 rigid cone, which rests on an articulation formed by two great 

 cells, round which it turns very easily. The least shock com- 

 municated to this long arm of tlie lever, is transmitted with great 

 readiness to the internal layers of the leaf, and develops the 

 phenomenon of turgescence, which is not produced when simply 

 the epidermis of the leaf is touched. These hairs are not true 

 hairs, but excrescences in intimate relation with the interior paren- 

 chyma ; hence their energetic action in the internal portions of 

 the leaf. 



Paris 



Academy of Sciences, Aug. 7.— Vice- Admiral Paris in the 

 chair. — The following papers were read :— Experimental critique 

 on glycffimia (continued), by M. Claude Bernard. He illustrates 

 three statements:— I. Glyccemia does not differ in carnivorous 

 and in herbivorous animals ; it is independent of alimentation. 

 2. In traversing the arterial system the blood contains nearly the 

 same proportion of sugar. 3. In the general venous system the 

 proportion of sugar is variable, but always inferior to that of the 

 arterial blood.— Observations of M. P. Thenard with reference 

 to M. Bernard's communication. He calls attention to capillary 

 affinity, and a mode he found of destroying it. He left a large 

 vessel of gelatinous alumina in a chamber where it froze during 

 winter. In spring he found the vessel filled with water, and, at 

 the bottom, a thin layer of an alumina, which as to its capillary 

 affinity, shared but little the properties of the frozen alumina. _ He 

 has practised the method artificially in purification of his black 

 acids. Now M. Bernard pours into a maximum solution of sulphate 

 of soda an equal volume of blood. The blood coagulates, then 

 by evaporation and coohng, crystallisation of the salt is effected. 

 This crystallisation, the author points out, is virtually the same 

 as his congelation.— On the alteration of urine ; reply to Dr. 

 Bastian, by M. Pasteur. He considers Dr. Bastian's reply as 

 aside from the point in discussion. The difference is solely with 

 regard to interpretation of the facts.— On the carpellary theory 

 according to the Loaseae (second part), by M. Trecul— Reply to 

 the last communication of M. Him, by M. Ledieu.— On radio- 

 meters of intensity, by M. de Fonvielle. The dissymmetry of 

 action necessary to rotation may be obtained by substituting a dis- 

 symmetry of figure, relatively to the axis, for dissymmetry of 

 substance or of coloration. The arrangement of feather mills 

 might be imitated, or that of cup anemometers, or that of screws 

 actuated by an air current, or that of the orreries turned by the 

 current from a Holtz machine.— On a new process for preparing 

 tinder wicks without poisonous substances, by M. Monier._ Oxide 

 of manganese is substituted for chromate of lead. The wicks are 



impregnated with sulphate of manganese, which is decomposed by 

 caustic soda, or they are simply immersed in a solution of per- 

 manganate of potash. — On the'phylloxerised spot (4 hectares) of 

 Mancey (Saone-et-Loire), by M. Rommier. The facts show that in 

 its progress northwards, the phylloxera is not prevented by the 

 greater coolness of climate, and that application of sulpho- 

 carbonates to advanced spots at the proper time, may reduce the 

 swarming, and save, for a long period, tlie neighbouring unat- 

 tached vineyards. — On determination of the carbonic acid con- 

 tained in waters (of irrigation, of drainage, of springs, of rivers, 

 &c.), by M. Houzeau. The method is to liberate successively, 

 in the gaseous state, the free and the combined carbonic acid, 

 and absorb by 5 cubic centimetres of a concentrated solution of 

 soda with addition of ^^^„ of oxide of zinc. The carbonic acid is 

 then estimated volumetncally by a method the author described 

 in Ann. de Chimieetde Physique. — On a new process of qualitative 

 testing and determination ot potash, by M. Carnot. He uses the 

 new reaction given by salts of potash in presence of hypo-sulphite 

 of soda and a salt of bismuth in a charged solution of alcohol. — On 

 the^different rotatory powers possessed by sugar-cane according to 

 the process employed for measuring them, by M. Calderon. — Pro- 

 cess for determining hydrocarbons, and especially fire-damp in 

 mines, by M. Coquillion. He composes a certain number of mix- 

 tures of air and protocarbonised hydrogen, introduces agiven quan- 

 tity of the mixture into a tube in which is soldered a palladium 

 spiral, reddens the wire, awaits cooling, then measures the 

 remaining gas. (Platinum wire gives frequent detonations in 

 hydrocarbons with air, but palladium does not. ) By comparison, 

 the quantity of fire-damp in a given atmosphere may be esti- 

 mated. — On the employment of chloride of calcium in watering 

 of streets, promenades, and public gardens, by M. Couste. He 

 calls attention to his experiments on the subject, previous to 

 those of M. Houzeau. — On some peculiarities of reflex move- 

 ments produced by mechanical excitation of the cranial dura 

 mater, by M. Rochefontaine. Such excitation on one side will 

 cause contraction of one or of several muscles of the face on the 

 same side, and for this a slight excitation suffices, or the animal 

 may be but partly anaesthetised. A stronger mechanic si stimu- 

 lation causes also movement of the limbs on the same side, and 

 a still stronger one movements of all four limbs. In the second 

 case the excitation must be transmitted directly to the corre- 

 sponding half of the chord ; and in the third there is bqth direct 

 and cross transmission ; the direct being more intense, how- 

 ever, for the movements on the corresponding side are stronger. 

 — Botanical affinities of the genus Neuropteris, by M. Renault. — 

 On the annual revision of the magnetic map of France, by MM. 

 Marie Davy, and Decroix. Table of declinations given. From 

 June, 1875, to June, 1876, the mean annual variation of Paris 

 was about — 0° 2' 12". 



CONTENTS Page 



A Physical Scihnck Museum 325 



CoHN ON THB Biology of Plants. By Prof. W. R. McNad . . . 326 



Fernkt's Physics 327 



The Chemistry of Light and Photography. By R. J. Friswell 328 

 Our Book Shelf : — 



" Les Insectes " 329 



LsTTERS to the Editor :— 



Protective Mimicry.— Francis Darwin ; Thomas R. R. Steb- 



BiNG ; R. Meldola 329 



Antedated Books. — R. Bowdler Sharps ; Another F.Z.S . . . 330 



Meteor Observations. — J. Edmund Clark 331 



The French Association 331 



The Science Degrees of the University of London 331 



Science in Italy. By C. Tomlinson, F.R.S 333 



The Volcano OF Reunion [With Illustrations) 333 



Arctic Fossil Flora 336 



Our Astronomical Column : — 



The Double-Star B.A.C. 1972 337 



The Second Comet of 1844 337 



New Nebulae 337 



The Norwegian North Atlantic Expedition 337 



Mr. O. C. Stone's Expedition to New Guinea. By R. Bowdler 



Sharps 338 



Abstract Report to "Nature" on Experimentation on Ani- 

 mals FOR the Advance of Practical Medicine, VI. By Dr. 



Benjamin W. Richardson, F.R.S 3-9 



Notes 341 



Societies and Academies 344 



