December 14, 1905] 



NA TURE 



167 



diopside of unusual habit, and a Carlsbad twin of albite 

 were described. — Note on the crystallisation of drops, 

 especially of potash-alum : J. Chevalier. The president 

 described observations made by Mr. Chevalier on the 

 1 rystallisation of drops of solution of potash-alum. These 

 generally yield in succession (a) birefringent spherulites ; 

 (6) octahedra; and (c) a fine rectangular network, (a) is 

 probably a less hydrated alum, and it becomes isotropic 

 on exposure to moist air by conversion into (b). (c) is 

 ordinary alum which is in a state of strain, owing to its 

 rapid crystallisation, and becomes white and opaque after 

 a time owing to the development of cracks. Drops observed 

 upon a slide under the microscope behave differently accord- 

 ing as they are in the metastable or labile condition. A 

 metastable drop inoculated with (a), (b), or (c) deposits 

 octahedra. A labile drop inoculated with (a) deposits 

 spherulites, but inoculated with (6) or (c) deposits the rect- 

 angular network. When a metastable drop containing 

 either octahedra or spherulites, or both, passes into the 

 labile condition (by cooling or by evaporation), they may 

 continue to grow unchanged. If, however, a fragment or 

 germ of octahedral alum be introduced into a labile drop 

 the network (c) is immediately produced. An alum crystal 

 growing in a labile solution is surrounded by a zone of 

 metastable liquid which prevents it from starting the net- 

 work (c) characteristic of a labile drop. Experiments were 

 made upon the action of various mineral substances in 

 inducing crystallisation in metastable and labile drops. 

 Among these the holosymmetric cubic crystals, and 

 especially galena, exercise a remarkable effect in producing 

 the network (c) in labile drops. — Note on the formation 

 of gypsum crystals in a disused well at chemical works : 

 C. J. Woodward. Groups of gypsum crystals were ex- 

 hibited which were found thirty years ago studding the 

 walls of an old well at Messrs. Chance's chemical works 

 at Oldbury. — Notes on minerals recently found in the 

 Binnenthal : R. H. Solly. The minerals described were 

 (i) Ilmenite, in brilliant crystals, displaying marked hemi- 

 hedrism and showing five new forms. It is associated 

 with quartz, adularia, magnetite and mica, on mica schist. 

 (2) Seligmannite ; an exceptionally large and well developed 

 crystal in dolomite. Unlike any previously described, it is 

 untwinned ; altogether forty-five forms were observed, of 

 which twenty-one are new. (3) Marrite ; two more crystals 

 of this rare mineral were found, one tabular and the 

 other sharply pointed in habit. (4) Proustite ; a minute 

 crystal deposited on a crystal of rathite. (5) Trech- 

 tnannite ; a crystal of this rare mineral displaying asym- 

 metric hemihedrism, deposited on a crystal of binnite. 

 (6) Hyalophane ; in crystals of an unusual green colour. 



Entomological Society, November 15. — Mr. F. Meirifield, 

 president, in the chair. — Exhibitions. — A flower-frequenting 

 beetle from the Transvaal, illustrating a remarkable device 

 for the cross-fertilisation of flowers, one of the front feet 

 being tightly clasped by the curiously formed pollinia of 

 an Asclepias : Mr. Arrow. — A remarkable specimen of 

 Agrotis tritici, taken this year at Oxshott, bearing a close 

 resemblance to .1. agathina, with which it was flying over 

 heather : W. J. Kayo. The specimen was a good example 

 of syncryptic resemblance brought about by the common 

 habit of resting on heather. — A specimen of Forficula 

 auricularia taken by Mr. R. A. R. Priske at Deal in 

 September, 1905, having the left cercus normal, while the 

 right was that of var. forcipata : W. J. Lucas. — Forms of 

 South African Pierine butterflies taken during the dry 

 season of the present year, together with specimens of the 

 same species for comparison taken in the same localities : 

 Dr. F. A. Dixey. He said that his exhibit illustrated the 

 fact, now widely recognised, that these forms varied in 

 general correspondence with the meteorological conditions 

 prevailing at the different seasons. — A long series of Hemero- 

 phila abruptaria bred by the exhibitor illustrating the pro- 

 portion of light and melanic forms derived from a light 

 male and a light female : E. Harris. — A c? specimen of 

 Tortrix pronubana, Hub., taken by Mr. Harold Cooper 

 at Eastbourne, either at the end of September or the 

 beginning of October last : S. Image. The insect is new 

 to the British list. — Paper. — Hymenoptera-Aculeata, col- 

 lected in Algeria, part iii., Diploptera, by E. Saunders, 

 F.R.S. : Commander J. J. Walker. 



NO. 1885, VOL JT,~] 



Liniean Society, November 16— Mr. C. B. Clarke, 

 F.R.S. , vice-president, in the chair. — Exhibitions. — Speci- 

 mens of British water Ranunculi, showing the modifications 

 in the form of the leaves : H. and J. Groves. The authors 

 pointed out that the species might be roughly grouped 

 under three headings : — (1) those in which only broadly 

 lobed aerial leaves were produced ; (2) those in which sub- 

 mersed multifid leaves with capillary segments were also pro- 

 duced ; and (3) those with multifid leaves only. — Photograph 

 showing, of the natural size, the otoliths from thirty-five 

 species of fishes, a collection made by the late Dr. David 

 Robertson : Rev. T. R. R. Stebbing. — Leaf and seed of 

 Macrozamia spiralis from Queensland, where the plant is 

 stated to cause symptoms of paralysis of the hind-quarters 

 of cattle eating the leaves : E. M. Holmes. The chemical 

 nature of the constituents of the plant appears to be un- 

 known. — Papers. — Contributions to the embryology of the 

 Amentiferae, part ii., Carpinus Betulus : Dr. Margaret 

 Benson, Miss E. Sanday, and Miss E. Berridge. 

 Material was collected early in July, 1902, and 1904, and 

 more than 600 series of sections were obtained through 

 ovules containing the earlier stages in the development of 

 the embryo-sacs, . until the first segmentation of the de- 

 finitive nucleus had occurred. Former observations (see 

 part i. in Trans. Linn. Soc, ser. ii., bot. iii. (1894), pp. 

 409-424) were confirmed, and the following new facts 

 obtained. The polar nuclei meet at the neck of the csecum, 

 descend together, and generally fuse near its base. The 

 pollen-tube enters the sac in their vicinity, and emits one 

 gamete into the caecum, usually by means of a short spur. 

 The gamete then makes its way to the definitive nucleus. 

 The other gamete is carried up by the tube to the egg, with 

 which it fuses. The egg then becomes clothed with a wall, 

 and segmentation commences. — The membranous labyrinth 

 of five sharks : Prof. C. Stewart, F.R.S. 



Paris. 

 Academy of Sciences, December 4. — M. Troost in the 

 chair. — Contribution to the study of the distribution of the 

 tsetse fly in French West Africa : A. Laveran. Since 

 writing the earlier notes on the same subject, the author 

 has accumulated additional material, details of which are 

 now given. — On the deformation of quadrics : C. 

 Guichard. — On Bode's law and the inclinations of the 

 planetary equators to the ecliptic : E. Belot. — On the 

 intrinsic brightness of the solar corona during the 

 eclipse of August 30, 1905 : Charles Fabry. The instru- 

 ment used was a modified Mascart photometer. The 

 intrinsic brightness found was, at a distance of 5' from 

 the edge of the sun, and in the direction of the equator, 

 about 720 candles per square metre, or about 0-28 the 

 intrinsic brightness of the lunar surface. — The inertia of 

 tin electrons : Marcel Brillouin. — On certain experiments 

 relating to the ionisation of the atmosphere, executed in 

 Algeria on the occasion of the total eclipse of August 30, 

 1905 : Charles Nordmann. A continuous record of the 

 positive ions present in the air was obtained, the instru- 

 ment destined to measure the amount of negative ions 

 being broken in transit. The curve given by the ionograph 

 showed a marked minimum during the eclipse, thus agree- 

 ing with the vi»ws of Lenard, Elster and Geitel, who 

 regard the solar radiation as one of the direct or indirect 

 factors in atmospheric ionisation. — On the equilibrium 

 diagram of the iron-carbon alloys : Georges Charpy. The 

 influence of the rate of cooling on the composition of the 

 casting has been neglected by the earlier workers on this 

 subject. Details are given of a study of an alloy contain- 

 ing 290 per cent, of carbon, for which the Bakhuis- 

 Roozeboom diagram is drawn. — The action of silicon on pure 

 aluminium ; its action on impure aluminium ; silico- 

 aluminides : Em. Vigouroux. Silicon does not form a 

 definite compound with pure aluminium, but in presence 

 of a third metal silicides of aluminium and this metal are 

 formed, well defined crystallised substances, silico- 

 aluminides. — On a-decahydronaphthol and the octahydride 

 of naphthaline : Henri Leroux. a-Naphthol, treated with 

 hydrogen by the method of Sabatier and Senderens, gives 

 the decahydride, the details of the preparation and proper- 

 ties of which are given in the present note. Treated with 

 a dehydrating agent it loses a molecule of water and gives 

 an octahydride of naphthalene. — On victorium and the 



