452 



NATURE 



[March io, 1892 



The structure of organs of the skate and torpedo are com- 

 pared at length, and it is shown that in the case of the torpedo 

 all the non-essential structures are absent ; while the all-essential 

 part, the electric layer or plate, closely resembles the corre- 

 sponding layer or plate in the skate ; the electric layer of R. 

 circularis being especially like that of the torpedo. 



In considering the modifications of the electric organ in the 

 skate genus, it is shown that in all the British species, with the 

 exception of R. radiata, R. circularis, and R. fullonica, the 

 elements are in the form of disks. In the three exceptions the 

 elements are more or less cup-shaped. In R. radiata, as 

 described in a former paper, they are in the form of thick-walled 

 shallow cups. The electric plate, apparently a greatly enlarged 

 motor plate, lines the cup, which throughout resembles an 

 ordinary striated muscle. In R. cifxularis, a more specialized 

 member of the group, the electric elements are larger and better 

 developed. The cups are deep and well moulded, and the 

 electric layer is even more complex than in R. batis ; at least, it 

 more closely resembles the electric layer of the torpedo. 

 Further, the cups are invested by a thick nucleated cortex, from 

 which a number of delicate short processes project — the first 

 appearance of the long prongs found in R. batis. In R. fullonica 

 the electric elements stand nearly midway between the only 

 partially transformed muscular fibres of R. radiata and the 

 complex disks of A', batis. The cups in R. fullonica are less 

 deep than in R. circtilaris ; and while the electric and striated 

 layers appear to be all but identical in the two species, the 

 cortex is decidedly more like that of R. batis. The short simple 

 processes of R. circularis are represented in R. fullonica by 

 processes, often complex, which, by projecting freely from the 

 outer surface of the cup, give it an irregular villous appearance, 

 and at once suggest the processes or prongs which are so 

 characteristic of the alveolar layer of R. batis. 



After giving a summary of his observations on the electric 

 organ of the skate, the author concludes by pointing out that it 

 is not yet possible to indicate by what method the electric 

 organs of fishes have been produced. 



"On the Organization of the Fossil Plants of the Coal- 

 Measures. Part XIX." ByW. C.Williamson, LL.D.,F.R.S., 

 Professor of Botany in the Owens College, Manchester. 



Physical Society, February 12.— Annual General Meeting. 

 — Prof. W. E. Ayrton, F.R.S., President, in the chair. — The 

 Report of the Council was read by the President, as were also 

 the obituary notices of Prof. W. Weber, late Honorary Member, 

 Mr. W. G. Gregory, and Prof. James Couch Adams. A list 

 of additions to the library accompanied the Report. Dr. E. 

 Atkinson read the Treasurer's statement, showing a gain of 

 about ;£'240. On the motion of the President, the Reports of 

 the Council and of the Treasurer were unanimously adopted. 

 Prof. Van der Waals was elected an Honorary Member of the 

 Society. Prof. Reinold proposed a cordial vote of thanks to the 

 Lords of the Committee of Council on Education for the use of 

 the rooms and apparatus in the Royal College of Science. This 

 was seconded by Prof. S. P. Thompson, and carried unani- 

 mously. A similar vote was accorded to the auditors, Dr, 

 Fison and Mr. H. M. Elder, on the motion of Mr. W. Baily, 

 seconded by Dr. C. V. Burton. The following gentlemen were 

 declared duly elected to form the new Council : — President : 

 Prof. G. F. Fitzgerald, F.R.S. Vice-Presidents: Prof. A. W. 

 Riicker, F.R.S., Walter Baily, Prof. O. J. Lodge, F.R.S., 

 Prof. S. P. Thompson, F.R.S. Secretaries: Prof. J. Perry, 

 F.R.S., and T. H. Blakesley. Treasurer: Dr. E. Atkinson. 

 Demonstrator: C. Vernon Boys, F.R.S. Other Members of 

 Council : Shelford Bidwell, F.R.S., Dr. W. E. Sumpner, Major- 

 ■General E. R. Festing, R.E., F.R.S., J. Swinburne, Prof. 

 J. V. Jones, Rev. F. J. Smith, Prof. W. Stroud, L. Fletcher, 

 F.R.S., G. M. Whipple, James Wimshurst. A vote of thanks 

 to the officers of the Society was proposed by Mr. Swinburne, 

 seconded by Mr. A. P. Trotter, and qarried unanimously. The 

 Chairman then invited suggestions towards improving the work- 

 ing of the Society. In response. Prof. S. P. Thompson said 

 that as the Society had been established fifteen or sixteen years, 

 and had amply justified its existence, the time had now arrived 

 ior giving fuller recognition to the privileges of members. He 

 thought they had earned the right to be called " Fellows," and 

 that this ought to be signified by some distinctive title. Mr. J. 

 Swinburne suggested that before papers were brought before the 

 meetings they should be read by a Member of Council. If suit- 

 able, they should then be printed, and proofs sent to members who 



NO. 1167, VOL. 45] 



applied for them. Mathematical papers could then be taken as 

 read ; and the discussions would be more interesting and to 

 the point. It would also be an advantage if communications on 

 kindred subjects could be taken the same day, and discussed to- 

 gether. Papers on purely technical subjects should go to the tech- 

 nical societies. Prof. Ayrton, in reply to Mr. Swinburne, said the 

 members had the matter of papers in their own hands, for, as 

 pointed out in the Report of the Council, if they would only 

 send in the papers early enough, the Secretaries would be glad 

 to group them in the way suggested. Referring to Prof. Thomp- 

 son's remarks, he said he had often thought it would be an 

 advantage to have another class of members in the shape 

 of " Students," who should hold meetings amongst themselves. 

 Mr. A. P. Trotter said the Society was unique in many respects, 

 and thought it was not desirable to have different grades of 

 membership. Dr. C. V. Burton agreed with Mr. Trotter, and 

 said that even if Prof. Thompson's suggestion was adopted, 

 means should be provided that persons could be admitted into 

 the Society without claiming any distinction therefrom. Prof. 

 S. P. Thompson, referring to the communications brought before 

 the Society, said it was not necessary that all should possess 

 great novelty. Descriptions of new arrangements of apparatus, 

 of diagrams, and exhibits of modern instruments were of great 

 interest to members. The Chairman pointed out that at the 

 early meetings of the Society exhibitions of instruments were 

 frequent, and said the Council would be glad if instrument 

 makers would send apparatus to be shown at any of the meet- 

 ings. The meeting was resolved into an ordinary science 



meeting, and Messrs. W. R. Bower and E. Edsen were elected 

 members. — Prof. S. P. Thompson, F.R.S., communicated a 

 note on supplementary colours, and showed experiments on the 

 subject. As white light can be divided into pairs of " com- 

 plementary colours," so any coloured light, not monochromatic, 

 can be split up into pairs of tints ; these, the author, for want of 

 a better name, has called " supplementary colours." For pro- 

 ducing such colours two methods were used. In the first one, 

 a spectrum of the coloured light was formed by a direct-vision 

 spectroscope and recombined on a screen. By interposing a 

 narrow prism between the spectroscope and screen, a portion of 

 the spectrum was separated from the rest, and various pairs of 

 supplementary colours thereby obtained. In the other method, 

 polarized light, a quartz plate, and a double image prism were 

 used to form two patches of complementary colours. On inter- 

 posing a coloured medium the patches became supplementary, 

 and varied in tint as the prism was rotated. The chief pecu- 

 liarity of supplementary colours was the great variety of tints 

 that could be obtained from a single medium, permanganate of 

 potash in dilute solutions being particularly rich in this respect. 

 The author had also noticed that the eye was not very sensitive 

 to orange-coloured rays. When experimenting by the second 

 method, he had observed that with any composite light one of 

 the supplementary patches could be got of a grayish hue, and 

 the other nearly a pure spectrum tint. He thus unexpectedly 

 verified Abney's law that any colour could be produced by 

 diluting some spectrum tint with white light. Captain Abney 

 said it was very interesting to see the gray colour and the supple- 

 mentary colours shown by the author. General Festing and 

 himself had experimented on colour phenomena l)y methods 

 quite different from those used by Prof. Thompson, for they had 

 matched colours by adding white light to pure spectrum tints 

 until a match was produced. Greater purity of colour could be 

 obtained in this way.— A paper on modes of representmg 

 electromotive forces and currents in diagrams, by Prof. S. P. 

 Thompson, F.R.S., was postponed. 



Chemical Society, February 18.— Prof. W. A. Tilden, 

 F.R.S., Vice-President, in the chair.— The following papers 

 were read :— A search for a cellulose-dissolving (cytohydrolytic) 

 enzyme in the digestive tract of certain grain-feeding animals, 

 by H. T. Brown. The author and G. H. Morris have recently 

 shown that during germination of grass-seeds the cell-membrane 

 of the endosperm is broken down and destroyed by a specific 

 cellulose-dissolving enzyme, or cytohydrolyst ; such disintegra- 

 tion of the cell-wall being a necessary operation, as otherwise 

 the cell-contents would not readily come under the influence of 

 the very indiffusible starch and proteid-dissolving enzymes 

 secreted by a certain layer of cells in the embryo. As it \yas 

 found by the author that the analogous siarch-hydrolyzing 

 enzymes of animal saliva and of the pancreatic secretion ex- 

 periences the same difficulty in traversing the thin cell-mem- 



