April 20, 1899] 



NA TURE 



599 



larvx were identified by Mr. Burr as those of a species of 

 Pociilocenis, probably /'. vi/latiis, Klug. — Mr. Blandford gave 

 an account of a paper by Dr. A. Ribaga, published in the 

 " Rivista di Patologia Vcgetale," v. p. 343, on an asymmetrical 

 structure occurring in the adult female of the common bedbug, 

 and apparently hitherto overlooked, although it communicated 

 with the exterior by a conspicuous notch in the fourth abdominal 

 segment, midway between the median line and the lateral 

 margin. This structure consisted of a large quasi-glandular 

 mass of unUnown nature in which was encapsuled an organ 

 consisting of fibres, the free ends of which terminated in minute 

 cbitinous spines in a recess lying under the fourth abdominal 

 segment. The adjacent margin of the fifth segment was 

 thickened and set with strong teeth. The non-glandular part 

 of this singular structure was conjectured by its discoverer to 

 be a siridulating organ ; but no evidence of stridulation had 

 been obtained. It w.as certainly far more complex than most, 

 if not all, other stridulating organs known to exist in insects. — 

 Mr. G. J. Arrow communicated " Notes on the Rutelid genera 

 Anomala, lilinula, Pof^illia, and Strigodernta.^* 



Mathematical Society, April 13. — Lieut. -Colonel Cunning- 

 ham, R.E., Vice-President, in the chair. — The chairman briefly 

 referred to the loss the Society had sustained by the recent 

 death of its foreign member, Prof. Sophus Lie. — Mr. A. B. 

 Kempe, F.R.S., having taken the chair, Lieut. -Colonel Cun- 

 ningham read a paper on conformal division. Major Mac- 

 Mahon, F. R.S., Messrs. Lawrence, Western, and the chairman 

 joined in a discussion on the paper. — The following papers were 

 communicated in abstract. On the characteristic invariants of 

 an asymmetric optical system, Mr. T. J. Bromvvich. The re- 

 duced path from one point to another is expressed in terms of 

 the directions of the ray at those points. It is now found 

 possible to put down eight invariants by inspection (only six 

 are independent). These are expressed in terms of those given 

 by Prof. Sampson {Proceedings, vol. xxix. ). The remainder 

 of the note consists in bringing the reduced path to two canonical 

 forms and some geometrical interpretations. — Concerning the 

 four known simple linear groups of order 25920, with an 

 introduction to the hyper- Abelian linear groups. Dr. L. E. 

 Dickson. (l) On the direct determination of stress in an elastic 

 solid with application to the theory of plates ; (2) on the stress 

 in a rotating lamina ; (3) the uniform torsion and flexure of in- 

 complete tores with application to helical springs, Prof. J. H. 

 Michell. — The theorem of residuation, Noether's theorem, and 

 the Riemann-Roch theorem, Dr. F. S. Macaulay. — Impromptu 

 communications were made by Messrs. Ilargreaves, Heppel, 

 Koseveare, Western, and the chairman. This last drew atten- 

 tion to the following curious properties of the number 7, \\z. : — 



iS' = + I, 19' = - I (mod, 7- and 7') 



1353^ = + I, 1354' = - I (mod. 7^ and 7=) 



826813 = + I, 82682^ S - 1 (mod. 7'' and f) 



but these properties do not extend to 7' and 7'. 

 Edinburgh. 

 Royal Society, April 3.— Prof. Duns in the chair. — Dr. R. 

 Kennedy read a paper on the restoration of coordinated move- 

 ments after nerve section, of which the following are some ol 

 the main results. The peripheral segment of the divided sciatic 

 nerve was rotated to the extent of a semicircle before reunion 

 to the central .segment by means of suture. As a result 01 

 this, the nerve fibres of the central segment were brought into 

 apposition with non-corresponding peripheral segments, and 

 the nerve thus placed in the best conditions for the formation 

 of new paths for the nervous impulses. Restoration of co- 

 ordinated movements commenced on the seventh day after the 

 operation, and was complete from the fourteenth to the twenty- 

 first day. Despite this early restoration of function, the peri- 

 pheral segment showed the presence of Wallerian degeneration 

 and of complete regeneration of young nerve fibres, showing 

 that early restoration of function was not due to healing by 

 so-called first intention, but, instead, to regeneration of the 

 peripheral segment. In one case in which the two segments 

 of the drvided sciatic were united accurately in the old relation- 

 ship, an exactly parallel course as regards the time taken for 

 restoration of function was exhibited. — A paper was also com- 

 municated by Mr. Bellyse Baildon, at present lecturer in 

 English in the University of Vienna, on the rimes in the 

 authentic poems of William Dunbar. 



NO. 1538, VOL. 59] 



Paris. 



Academy of Sciences, April 10. — M. van Tieghem in the 

 chair. — On the interpretation of a limited number of observ- 

 ations, by M. Ilatt. The author discusses the method of dealing 

 with a measurement which deviates considerably from the others 

 when the total number of observations is small, recently proposed 

 by M. Vallier, and shows by means of a particular case that the 

 treatment suggested is not always trustworthy. — On the 

 applications of aluminium, by M. Henri Moissan. A criticism 

 of the recent work of M. Ditte on this subject. M. Moissan 

 points out that the aluminium used by M. Ditte in his researches 

 was not rigorously analy.sed, and that he attached no import- 

 ance to the small impurities of the metal, although these latter 

 may well have had a consider.able influence upon the results. 

 Aluminium is now produced in a nmch purer state than was 

 the case five years ago, a series of seven analy.ses, made in 

 1893, S'^'"g ^ mean percentage of 93^4, as against 97'8 percent, 

 for aluminium made four years later. The fact thai the 

 aluminium water vessels used in Madagascar were mounted in 

 contact with iron, may also have influenced the rapidity of 

 corrosion by the electrolytic action which would be set up at the 

 expense of the aluminium. — The production of electromotive 

 forces by the displacement of masses of lirjuid of different 

 conductivities submitted to the magnetic action, by M. R. 

 Blondlot. If a vessel containing two layers of zinc sulphate of 

 different concentrations, into each of which is plunged an 

 electrode of amalgamated zinc, is placed in a strong magnetic 

 field, when the liquids are mixed, differences of electromotive 

 force can be observed between the two electrodes by means of 

 a capillary electrometer. The theory of the results is fully 

 discussed. — The favourable action exercised by the pancreas on 

 alcoholic fermentation, by MM. R. Lcpine and Martz. — Appli- 

 cation of the criteriiim of Tisserand to the small planets, by M. 

 Jean Mascart. — On a dift'erential linear equation, by M. A. 

 Liapounoff. A discussion of the equation 



ax- 

 where /(.v) is a given continuous function of a real variable .»:, 

 having a period m, and jx. an arbitrary parameter. — A new inter- 

 pretation of the condition necessary for a double integral, taken 

 over a surface, to be independent of the boundary of the 

 surface, by M. Ch. Meray. — On the homography of the theory 

 of beams, by M. Andrade.— On surfaces of plain or spherical 

 lines of curvature, by M. Emile Waelsch. — Three formulic of 

 great generality relating to curves in space, by M. N. I. 

 llatzidakis. — On the effect of an increase or decrease of pressure 

 upon the electrolytic interrupter, by M. A. Le Roy. Both a 

 decrease and an increase of the atmospheric pressure interferes 

 with the working of the Wehnelt interrupter. — Some working 

 conditions of the Wehnelt electrolytic interrupter, by M. Paul 

 Bary. — On the variation of the electrical resistance of metals and 

 their alloys, due to torsion, by M. Coloman de Szily. To eliminate 

 the efl'ects of temperature, the alloy constantin was chosen, the 

 coefficient of increase of resistance with temperature of which is 

 extremely small, and the work carried out in a room the temper- 

 ature of which did not vary o°"i C. during the experiments. The 

 resistance was found to increase with the angle of torsion ; up to 

 the elastic limit of the material these two quantities were propor- 

 tional, but for higher angles of tor.sion the resistance increased 

 more rapidly than this. — Pointscorrelative to the points of Bravais, 

 by M. Pierre Lefebvre. — On a new method of preparing the 

 silicide of iron, FeSi, by M. P. Lebeau. A mixture of iron 

 filings and silicide of copper, the latter being in excess, is heated 

 in the electric furnace. The resulting ingot consists of 

 a mass of crystals of iron silicide, cemented together 

 by silicide of copper, the latter being readily removed by 

 dilute nitric acid. — The preparation and properties of a crystal- 

 lised sub-phosphate of copper, by M. Georges Maronneau. 

 Copper phosphate and carbon heated together in suitable 

 proportions in the electric furnace, give a crystallised compound 

 of copper and phosphorus of the composition Cu.^P. — On the 

 thermal properties of lime prepared at diflerent temperatures, 

 by M. Henri Gautier. Limes prepared at diflerent temperatures 

 .show remarkable difterences in the rate of hydration when 

 placed in water, lime fused in the electric furnace being so 

 slowly acted upon that it is possible to accurately determine 

 its density in water. It was thought that these differences 

 might be due to difi'erences in the molecular state of the 



