356 



NA TURE 



\A7lgUSt 23, 1877 



connective and endothelial elemenls, and the varying conditions 

 imposed upon them by their distinct functional endowments is of 

 essential import when we are dealing with the morbid brain." 

 The peri-cellular sac is then described fully, as well as its varied 

 contour dependent upon the form of the inclosed cell, method 

 of preparation, thinness of section, and the various physiological 

 and pathological conditions existing before death. The close 

 proximity of a capillary to these sacs was invariably observed, 

 and on close examination a connection bet«ixt the peri-vascular 

 and peri-cellular sheaths was clearly seen. Sections of the cortex 

 in new-born animals were then described, in which a linear arrange- 

 ment of the cells alongthe peri- vascular sheaths wasobserved, each 

 nerve-cell being separated by a clear space from the surrounding 

 neuroglia, the peii-vascular sheaths in the kitten being widely 

 distended. The nerve-cells in these cases were pyriform, and 

 apparently connected to their limiting sacs by a narrow stalk-like 

 process. The writer next dwells briefly upon the developmental 

 bearing of these facts. With regard to the explanation afforded 

 by some observers of the significance of these spaces in senile 

 atrophy, it is shown that whilst ihe large size and defined con- 

 tour may be due to shrinking of the degenerated protoplasm 

 of the nerve-cell, " yet the important point is to recognise these 

 spaces as natural structures in an unnaturally distended condi- 

 tion, for their large size appears to me to be due not only to 

 wasting and recession of the inclosed cell, but to a large accu- 

 mulation of lymph, the lymphatic channels, peri-cellular and 

 peri-vascular, being in a distended condition throughout." It is 

 next shown how readily the lymph current may be obstructed in 

 its flow towards the pia-mater, and how seriously such condi- 

 tions would affect the nutritive and depurative changes proceeding 

 in the lymph-sac — changes of so vital an importance in the main- 

 tenance of the functional activity of nerve-cells. The methods 

 employed in this investigation by Mr. Lewis, include ordinary 

 chrome hardening, the teasing process described by him in the 

 Monthly Microscopical Journal^ and the examination of films of 

 cortex obtained by his new freezing microtome. His paper is 

 illustrated by six drawings of the microscopic structure of the 

 cortex. 



Paris 



Academy of Sciences, August 13. — M. Peligot in the 

 chair. — The following papers were read : — Communication 

 from the Bureau des Longitudes on new operations of astro- 

 nomical geodesy, by M. Faye. This relates to the astro- 

 nomico-telegraphic junction of Paris with Neuchatel, Geneva, 

 and Lyons. — Engraving representing the aureola of Vtnus as 

 seen Irom the Island of St. Paul, by IVI. Mouchez. The pheno- 

 mena is given at three different stages. — A general law of 

 geometric curves concerning the common intervention of each 

 point of a curve and the tangent of this point, in questions of 

 geometrical positions or enveloping curves, by M. Chasles. — 

 New considerations on the localisation of cereliral centres regu- 

 lating the co-ordinated movements of written language and 

 articulated language (continued) by M. BouiUaud. He replies 

 to some recent objections by Dr. Fournie against localisation of 

 speech in the let cerebral hemisphere. — On the reproduction, by 

 photography, of the rice-grains of thesolarsurface, by IVI.Janssen. 

 He has succeeded in this in his solar photographs of thirty centi- 

 metres by means of a very short exposure, combined with strong 

 development. — On an example of reduction of Abelian integrals 

 with elliptic functions (continued), by Mr. Cayley. — On the best 

 conditions of employment of galvanometers, by M. du Moncel. 

 He gives an experimental verification of some mathematical 

 deductions. — Note on the central obturator inflamei-, by M. 

 Cosson. The state of dryness of the powder seems to have 

 (other things equal) an exceptional importance for the author's 

 apparatus. The Pyrenees mark the true line of separation 

 between the eocene and miocene port'ons of the tertiary 

 epoch, by M. Leymetie. — A message of sympathy was sent 

 to M. de Lesseps on account of his recent accident. — The 

 system of Sirius, by M. Flammarion. The orbit calculated 

 for the companion of Sirius differs from the orbit observed ; the 

 latter crossed the former in 1869 (having left it in 1862) and 

 going beyond it, has followed quite a different curve, wider 

 and less eccentric. M. Flammarion supposes that either the 

 companion will accelerate its motion and return to the west in 

 1892, or that there is another disturbing body nearer and more 

 rapid, not yet discovered. — Remarks, 1) propos of M. Faye's 

 communication on the relation between the sun-spots and varia- 

 tion of the magnetic declination, by M. Wolf. The anomalies 

 of the one class of phenomena are reproduced in the other, a 



strong evidence that both are produced by the same cause. —On 

 the equation of Riccati, by M. Genocchi. — Note on the curves 

 which have the same principal normals, by M. Niewenglowski. 

 — On the slipping [patinage) of the wheels of locomotives, by 

 M. Rabeuf The phenomenon is much more general and 

 complex (he finds) than is commonly supposed. The slipping is 

 almost nil in ascending an incline, and very pronounced in 

 descending. It increases rapidly with the speed, but appears 

 to be greater, with equal velocity, on descents than on ascents. 

 In descents it varies between 13 and 25 per cent. Its suppres- 

 sion, if possible, would realise a corresponding economy in fuel 

 and wear of machinery. — I'he regime of the winds, and evapora- 

 tion in the region of the Algerian cholts, by M. Angot. It is 

 shown from figures that the winds favourable to M. Roudaire's 

 project (viz., south, south-west and south-east) are to the unfa- 

 vourable winds in the ratio of I to 9 '4. Their vapours would be 

 almost wholly carried towards Sahara instead of Algeria. The 

 average layer of water estimated as removed ia twenty-four hours 

 from the projected sea is about 6 mm. This would raise to 

 seventy-eight millions of cubic metres the quantity required to 

 be brought by the canal of communication daily to keep the 

 lake-level constant. — On the vapour of hydrate of chloral, by 

 M. Troost. A second method (for determining equivalent in 

 volume) consists in first vaporising hydrate of chloral, then 

 introducing into the vapour a body capable of removing part of 

 the free vapour of water it may contain (pure neutral oxalate of 

 potash was used completely dehydrated in a stove at 100°). This 

 method led to the same conclusion as the first, viz., that hydrate 

 of chloral exists in the gaseous state, and so that its equivalent 

 corresponds to eight volumes. — Note on some properties of sul- 

 phide of cadmium, by M. Ditte. — On some general properties 

 of metallic sulphides, by MM. de Clermont and GuioL The 

 decomposition (here proved) of sulphides by water at 100° with 

 foi mation of metallic oxide and sulphuretted hydrogen, is thought 

 a fresh reason for regarding hydrogen as a metal ; it displaces 

 true me'als in these reactions, and forms a more stable sul- 

 phuretted compound. — On some points of the organisation of 

 Bryozoa, by M, Joliet. — On the fecundation of Echinodernrs, 

 by M. Giord. — Pyrophosphates in therapeutics ; their mode 

 of action, by MM. Pacquelin and Joly. Pyrophosphates, 

 far from being reconstitutive, as commonly supposed, are 

 purely foreign Irodies for the system, and their ingestion can only 

 increase its expenditure in the work of elimination, which their 

 presence necessitates. Any reconstitutive value attached tp them 

 is probably due to impurities. — On the physiological action of 

 Pan V&xeno{Geissosf>errmun lave, Baillon), by MM.Bochefontaine 

 and De Freitas. The active principle is a paralysing poison, 

 which appears to abolish the physiological properties of the 

 central grey nervous substance, and especially of the grey bulbo- 

 meduUary axis. — On anthracic bactcridics, by AL Toussaint. 



CONTENTS Page 



Mauritius OiiSERVATORV. By John Allan Broun, F.R.S. . . . 337 



Our Book Shblf : — 



De Crespigny's " New London Flora ; or. Handbook to the 



Bolauical Localities of tfie (Vletropotitan Districts " 338 



Matlliews' " Ethnography and Philology of the HidaLsa Indians" 338 



Whetham's " Across Central America '' 339 



Letters to the Editor ; — 



The Contractile Filaments of the Teasel.— Charles Darwin, 



F.R.S 339 



Relations between Sun and Earth. — E. D. Archibald .... 340 



Reproduction by Conjugation.— AuFREti W. Bennett .... 340 



The Greenland Foehn.— Joseph John Murphy 340 



Does Sunshine Extinguish Fire?— Charles Watson .... 341 



Our Astronomical Column : — 



The Opposition of Mars, 1S77 34Z 



The Satellites of Saturn 34, 



Satellites of Mars 341 



Section A. — Mathematical and Physical ■ . , 3^3 



Section D. — Biology. — Department of Anthropology. — Address by 



Francis Galton, F.R S 344 



Section G. — Mechanical Science 347 



Remarkable Plants, III— The Sensitive Plant (Mimosa 



piidica") (With Illustratioii) 34S 



Notes 35T 



An Algerian Inland Sea 353 



University and Educational Intelligence 354 



Scientific Serials , 355 



Societies and Academies 355 



