January 12, 1893] 



NATURE 



261 



representations of the muscular, alimentary, secretory, nervous, 

 and reproductive systems, and an account of the sense organs. 

 The paper is illustrated by ten double plates.— On the minute 

 structure of the gills of Palcemonetes varians, by Edgar J. 

 Allen, B. Sc. (Plate x.). It would seem that so far as the gills 

 of this crustacean are concerned, the statement made by 

 Haeckel and Ray Lankester, that the circulatory system of the 

 Decapods is everywhere closed, does not hold true. It would 

 also seem fairly certain that the masses of cells surrounding the 

 venous channels, in which Kowalevsky found litmus deposited 

 a few hours after its injection, exercise an excretory function. 

 In addition to these excretory cells, a large number of glandular 

 bodie^ occur in the axis of the gill, and these are of two kinds — 

 clear and reticulate glands. 



The number for November 1892 contains : — On the develop- 

 ment of the optic nerve of vertebrates, and the choroidal 

 fissure of embryonic life, by Richard Assheton, M.A. (Plates 

 xi. and xii. ). That the optic nerve is formed by the differentiation 

 of the cells of the optic stalk into nerve fibres, which conse- 

 quently lose connection with the inner wall of the optic cup, and 

 piercing the outer wall, make connection with the outer face 

 thereof, is held to be probable by such writers as Balfour, 

 Foster, Marshall, Haddon, and others, whilst the opinion that 

 it is formed by the growth of nerve fibres either from the retina 

 (outer wall of the optic cup) or from the brain, along the optic 

 stalk, but outside it and unconnected with it, is or has been held 

 by His, Miiller, Kolliker, Hertwig, Orr, and has been recently 

 supported by Keibel, Froriep, and Cajal. Schafer seems to be 

 uncertain whi>.h view to take. As the result of the author's 

 investif^ations in the frog and chick, he concludes that the optic 

 stalk takes no part in the formation of the nervous parts of the 

 organ of sight. The optic nerve is developed independently of 

 the optic stalk, and at first entirely outside it. The great 

 majority of the fibres forming the optic nerve arise as outgrowths 

 from nerve cells in the retina. — On the larva of Asterias vulgaris, 

 by George W. Field, M.A. ( Plates xiii. toxv.). — On the develop- 

 ment of the genital organs, ovoid gland, axial and aboral 

 sinuses in Amphiura squamata ; together with some remarks on 

 Ludwig's haemal system in this ophiurid, by E. W. MacBride, 

 B.Sc. (Plates xvi. to xviii.). Concludes that echinoderms agree 

 with other coelomata in the origin of their genital cells these 

 latter have at first an unsymmetrical position in echinoderms, 

 and afterwards take on a radially symmetrical disposition in 

 correspondence with the secondarily acquired radial form of the 

 body. The origin of these cells adjacent to the stone canal 

 suggests a comparison of the origin of the genital cells near the 

 nephridia in many annelids, but the homology of the stone 

 canal with a nephridium has yet to be proved. — On a new 

 genus and species of aquatic Oligochseta belonging to the 

 family Rhinodrilidae, found in England by W. B. Benham, 

 D.Sc. (Plates xix. and xx.). This new worm receives the name 

 of Sparganophilus tamesis ; it was found in some numbers in 

 the mud of the Thames, adhering to the roots of Sparganium 

 ramosum, near Goring ; the cocoon is drawn out to a point at 

 one end, while in the other it shows a narrow frayed end. As 

 the home of the Rhinodrilidae is America, the author suggests 

 that the cocoons of this worm may have been introduced into 

 the Thames amongst the roots of water plants, or attached to 

 timber from the United States. 



American Meteorological Journal, December. — Atmospheric 

 electricity, earth currents, and terrestrial magnetism, by Prof. 

 C. Abbe. The author has collected from various telegraph 

 companies particulars about electrical storms, which illustrate 

 the magnitude of the disturbances that frequently occur. The 

 present electrical and magnetic observatories, which usually 

 observe only some part of the whole series of phenomena, need 

 to be supplemented by completely equipped establishments 

 recording continuously the north-south, the east-west, and the 

 zenilhal-aniipodal differences of potential. The ordinary re- 

 cords of atmo pheric electricity give merely the difference of 

 potential of the earth and a point in the atmosphere defined as 

 the end of the water-dropping collector. — Notes on the use of 

 automatic rain gauges, by J. E. Codman. Observations were 

 made continuously for three years with the object of showing 

 what difference the size of the gauges would make in the 

 amount of rainfall collected. The largest gauge had a diameter 

 of over 22 inches, and the smallest 2 inches. The results show 

 that the size of the gauge made no practical difference. He 

 also gives the results of rainfall collected in gauges erected at 



NO. I 2 II, VOL. 47] 



various heights on a mast. The result showed that a gauge at 

 an elevation of 50 feet or less above the surface of the ground 

 will collect the same amount as one on the ground, provided 

 both are situated in a position not affected by counter currents 

 of air. This result agrees with that found by Prof. Hellmann 

 in his experiments at Berlin. — Sunshine recorders, by Prof. C. 

 F, Marvin. Thus far two methods only have been in general 

 use, (i) the focussing of the rays of the sun by means of a glass 

 sphere and obtaining a burn on the surface of a card, and (2> 

 the photographic method, producing a trace on sensitized paper. 

 The first method records only bright sunshine, while the latter 

 method is more sensitive and records fainter sunshine. Prof. 

 Marvin has improved a method first developed by D. T. Maring 

 of the Weather Bureau, consisting in principle of a Leslie 

 differential air thermometer, mercury being used to separate the 

 air in the two bulbs. When properly adjusted and exposed to 

 sunshine the lower blackened bulb becomes heated and causes 

 the column to rise above a platinum point and close an electric 

 circuit. The instrument, of which a drawing is given, is said 

 to respond promptly to sunshine and shadow. The other articles 

 are : — Late investigation of thunderstorms in Wisconsin, by W. 

 L. Moore. — Observations on the aurora of July 16, by T. W. 

 Harris, and Temperature sequences, by Prof. H. A. Hazen. 



The articles in the lournal of Botany for November and 

 December are mostly of interest to students of British botany. 

 Mr. F. J. Hanbury adds two more to his new species of 

 Hieraciuin, H. britannicum and H. caniceps ; Mr. Bagnall de- 

 scribes a new species of bramble, Rubus mercicus from the Mid- 

 land counties ; and Mr. W. H. Pearson a new British liverwort, 

 Scapania aspera. Mr. G. F. Scott Elliot contributes some use- 

 ful hints on botanical collecting in the tropics. 



SOCIETIES AND ACADEMIES. 



London. 



Royal Society, December 8, 1892. — " On the Photographic 

 Spectra of some of the Brighter Stars." By J. Norman Lockyer, 

 F.K.S. 



The present communication consists of a discussion of 443 

 photographs of the spectra of 171 stars, which have been obtained 

 at Kensington and Westgate-on-Sea during the last two years. 



The chief instrument employed in this work has been a 6-inch 

 refracting telescope in conjunction with — at different times — 

 objective prisms of ']\° and 45° respectively. 



By this method the time of exposure is short, and good defi- 

 nition, with large dispersion, is easily secured. The spectra thus 

 obtained will bear enlargement up to thirty times without much 

 sacrifice of definition. 



The 30-inch reflector and slit-spectroscope at Westgate-on- 

 Sea have also been used in the inquiry. 



My object has not been so much to obtain photographs of the 

 spectra of a large number of stars as to study in detail the spectra 

 of comparatively few. 



In the classifications of stars adopted by others from a con- 

 sideration of the visual observations, only the broader differences 

 in the spectra have been taken into account. Prof. Pickering 

 has more recently employed a provisional classification in con- 

 nection with the Henry Draper Memorial photographs of stellar 

 spectra, but this chiefly relates to photographs taken with small 

 disper-ion. With larger dispersion it becomes necessary to deal 

 with the presence or absence of individual lines. 



In the first instance, the various stars of which the spectra 

 have been photographed at Kensington have been arranged in 

 tables, without reference to any of the existing classifications, 

 and taking into account the finer details. The basis on which 

 the main tabular divisions of the spectra are founded is the 

 amount of continuous absorption at the blue end. This dis- 

 tinction was not possible in the case of the eye observations. 



The stars included in the first table are characterized by the 

 absence of any remarkable continuous absorption at the blue end, 

 and by the presence in their spectra of broad lines of hydrogen. 

 These have been further classified in four sub-divisions, depend- 

 ing on the presence or absence of other lines. 



In the stars of the second table there is a considerable amount 

 of continuous absorption in the ultra-violet, and the spectra 

 beyond K are very difficult to photograph as compared with the 

 stars of the first table. In these stars the thickness of the hydro- 



