April 7, 1881] 



NA TURE 



547 



Removing the pentagonal nen'e-ring has no effect at all upon 

 the pedicellaria; or on the local reflex action of the spines ; both 

 these organs continue to close round an instrument of stimulation. 

 But the general co-ordination of the spines is totally and perma- 

 nently destroyed — their i)ristling movements no longer servnig to 

 convey the animal from a source of irritation, but only causing 

 the anmial aimlessly to gyrate. This shows that the pentagonal 

 nerve-ring has in large measure the function of a nerve-centre. 

 The same thing is shown by the effect of its removal upon the 

 righting movements. These are gravely impaired, though not 

 wholly destroyed — four in twelve specimens so mutilated con- 

 tinuing able to right themselves. These facts, together with the 

 fact of separate segments of echinoderms behaving in all respects 

 like entire animals, prove that the nervous system is in function, 

 as in structure, everyv\here both central and peripheral ; although 

 the impairing influence exerted on the co-ordination both of the 

 spines and pedicels by removal of the pentagonal ring, proves 

 that this ring has a more centralising function than any other part 

 of the nervous system. 



Chemical Society, March 30. — Anniversary Meeting. — The 

 president. Prof. Roscoe, gave his annual address. He con- 

 gratulated the Society omits flourishing condition. At no period 

 in its hi^tory had the number of Fellows been so large, whilst 

 the number of papers read during the past twelve months had 

 increased both in number and in importance. The research fund 

 founded by Dr. Longstaff had done much for the progress of 

 science. The President touched upon the more important dis- 

 coveries of the year. The supposed decomposition of chlorine 

 and iodine by Victor Meyer lias been found to be capable of 

 another explanation. The solar and stellar evidence of the 

 decomposition of metals accumulated by Mr. Lockyer ha^ not 

 yet found general acceptance by chemists. Capt. Abney and 

 Col. Festing have discovered that the organic radicals methyl, 

 ethyl, &c., give characteristic absorption spectra in the infra-red 

 part of the spectrum. Baeyer has succeeded in preparing indigo 

 artificially, and its manufacture on the commercial scale is rapidly 

 progressing. The .Society has lo$t by death ten Fellows, includ- 

 ing Sir B. Brodie, Dr. Stenhouse, Prof. W. H. Mdler, and 

 Mr. Tennant. — The Longstaff medal was presented to Prof. 

 Thorpe of the Yorkshire College, Leeds, as the Fellow who 

 had done the most to promote chemical science by research. — 

 The reports of the President and Treasurer w ere received and 

 adopted, and the Officers and Council elected for the ensuing 

 year. Piesident, H. E. Roscoe. Vice-Presidents : F. A. Abel, 

 Warren De La Hue, E. Frankland, J. H. Gladstone, A. W. 

 Hofmann, W. Odling, Lyon Playfair, A. W. Williamson, A. 

 Cram Brown, J. Dewar, J. H. Gilbert, A. V. Harcuurt,- J. E. 

 Reynolds, J. Young. Secretaries: W. H. Perkin, H. E. Arm- 

 strong. Foreign Secretary, Hugo Miiller. Treasurer, W. J. 

 Russell. Council : F. D. Brown, M. Carteighe, H. McLeod, 

 G. H. Makins, E. J. Mills, W. C. Roberts, C. Schorlemmer, 

 J. M. Thomson, C. M. Tidy, W. Thorp, T. E. Thorpe, R. 

 Warington. 



Physical Society, March 26. — Prof. Fuller in the chair. — 

 New member Mr. Lewis Wright, author and editor. — Dr. 

 James Moscr read a pai er on electrostatic induction, especially 

 relating to the branching of the induction in the differential 

 inductometer and in the electrophorus. The author's experi- 

 ments bore out the hypothesis of induction as enunciated by 

 Faraday. Prof. Ayrton suggested the importance of adding 

 guard-nngs to the snail. plates of the five-plate indu;tometer or 

 balance, since without these mathematical calculations could not 

 be accurately applied, and the experimental determination of 

 specific inductive capacity would be doubtful. Dr. Moser 

 pointed out that though the theory was not absolutely correct 

 it lay with the experimenter to get results very approximately 

 correct. — I'rof. keinold, one of the secretaries of the Society, 

 read a pa er by himself and Prof. Riickert on the electrical 

 resistance of liquid films w ith a revision of Newton's scale of 

 colours. The experiments were in continuation of those pub- 

 lished by the authors in 1877. Their object was to determine 

 whether a film thinning under the action of gravity gave any 

 evidence, iiy a change in its specific resistance, of an approach to 

 a thickness equal to tvvice the radius of molecular attraction, 

 and alsii to devise a method of finding the amount of water 

 which ijiight be absorbed by or evaporated from it. The thick- 

 ness of the films was determined from their colour by means of 

 two beams reflected from different mirrors on them. — Newton's 

 scale of c 'lours was revised by observations on Newton's rings, 

 and partly by more than 2000 observations on the rings them- 



selves. The thicknesses determined by direct observations 

 on Newton's rings and those in the corrected table rarely 

 differ by i per cent., while Newton's scale in parts differs 

 from both by as much as 10 per cent, of the thickness. 

 The films were formed from a solution of oleate of soda in 

 glycerine, w ith a little nitrate of potash added to increase their 

 electric conductivity. They were blown in a gla.ss ca-e from 

 which the outer air could be excluded. Precautions were taken 

 to keep the air in contact with the films inside the case at a 

 proper humidity. These consisted in placing disks containing 

 the solution at the bottom of the case and .suspending within it 

 sheets of blotiing-paper, the Inver edges of which dipped into 

 the liquid. A hair hygrometer indicated changes in the humidity 

 of the interior. The resistance of the films was measured by 

 piercing them with gold wires, which were connected wiih the 

 electrodes of a quadrant electrometer. The resistance of the film 

 between the needles was calculated by comparing the deflection 

 caused by the difference of potential of the two wires when a 

 current was passing through the film with that produced by the 

 difference of (lotential above and below a known resistance placed 

 in the same circuit. The specific resistance of the liquid from 

 which tlie films were formed ^^ as measured by a method identical 

 in principle with the above. The liquid was contained in a glass 

 tube with turned-up ends. Platinum wires were cemented into 

 small holes drilled in the straight part of the tube, and their 

 difference of potential compared with that of two points in the 

 same circuit separated by a known resistance. This method has 

 the gieat advantage of getting rid of any difficulties connected 

 with polarisation. Test experiments on sulphuric acid proved 

 the method to give results agreeing with those of Kohlrausch, who 

 employed alternating currents and Wheatstone's bridge. The 

 results of the experiments may be summed up as follows : — It is 

 difficult to form a soap film under conditions precluding a slight 

 evaporation or absorption of water, but the more nearly these 

 conditions are attained the more closely does the specific resist- 

 ance of the film agree with that of the liquid in mass. The films 

 observed under the most favourable conditions obeyed Ohm's 

 law with great accuracy, and much better than the others. The 

 films indicate no approach to a thickness equal to the diametei 

 of molecular attraction. A soap-film may even in an inclosed 

 space readily loose 23 out of 57"7 volumes of water contained in 

 every 100 volumes of the solution, when special precautions are 

 not taken to maintain the surrounding space in a constant hygro- 

 raetric condition. Prof. Ayrton suggested that in measuring the 

 liquids and film the distance between the electrodes should be 

 varied. Prof. Guthrie pointed out that the results of Prof. 

 Reinold and Kohlrausch agreed with his own in showing that 

 the conductivity of liquids obeyed Ohm's law. 



Geological Society, March 23. — Robert Etheridge, F.R.S., 

 president, in the chair. — Rev. Daniel Button and Capt. George 

 Ernest A. Ross were elected Fellows of the Society. — The fol- 

 lowing communications were read : — The Upper Greensands and 

 chloritic marl of the Isle of Wight, by C. Parkinson, F.G.S. 

 In this paper the author described the Upper Greensand as ex- 

 posed at St. Lawrence and along the Undercliff. At the base 

 of the St. Lawrence Cliff there are hard bands of blue chert 

 from which astaciform Crustacea have been obtained ; and quite 

 recently, in a large boulder of the same material lying on the 

 beach, there were found the remains of a Chelonian, referred by 

 Prof. Owen to the family Paludinosa, and named by him Pla- 

 stremys lata. The presence of these fre-hwater organisms was 

 thought to imply a connection with the Wealden continent. The 

 chert-bed, 2 feet thick, was regarded by the author as marking 

 the boundary between the Gault and the Greensand. Above it 

 the author de-cribed 56 feet of compact red and yellow sands, 

 of which the first 20 feet are unfossiliferous, the upper 32 feet 

 show traces of organic remains; between them there is a fossili- 

 ferous zone 4 feet in thickness, containing Ammonites inflatiis, 

 A.auritus, and species of Ponopcra,CuciilliTa,'Arca, anATrigonia, 

 and immediately below this a separate band containing an un- 

 determined species of Ammonite. These sands are followed by 

 38 feet of alternate beds of hard chert and coarse greensands, 

 having at the bottom 6 feet of inferior building-stone sur- 

 moimted by 5 feet of freestone. The latter contains Ammonites 

 rostratiis, and the cherts various fossils, chiefly bivalves. Cla- 

 thraria Lyelli also occurs at this level. Above the greensands 

 come 6 feet of chloritic marl :" the upper 34 feet fossiliferous, 

 with a base of hard phosphatic nodules containing crushed spe- 

 cimens of Pecten asper ; the lower 2^ feet compact, with darker 

 grains and few fossils. The author compared the sections of 



