May 29, 1890] 



NATURE 



117 



Extension Scheme is to be held in Cambridge on July 9 and lo' 

 Courses of lectures and practical work are to be arranged for 

 students for local centres who are to reside in Cambridge during 

 the month of August. 



A very interesting report on the progress of the Extension 

 movement by Dr. R. D. Roberts appears in the Cambridge 

 University Keforter of May 27. The account he gives of the 

 enthusiasm and energy displayed by certain of the Students' 

 Associations attending Extension lectures is most encouraging, 

 and shows how wide-spread is the influence for good exerted by 

 the University in this connection. 



SCIENTIFIC SERIALS. 



The Quarterly Jojiriial of Microscopical Science for April 

 1890 contains papers on Pliymosotna varians, Selenka, by 

 Arthur E. Shipley (plates i. to iv.). The material for this paper 

 was collected by Mr. Weldon in the Bahama Islands, where the 

 species was fairly abundant in the soft coral rock. The general 

 morphology and minute structure of this animal are described in 

 great detail, and accompanied by some excellent illustrations ; 

 the head of Phymosoma is surrounded by a stiffened vascular 

 horseshoe- shaped lip, the dorsal ends of which are continuous 

 with the ends of a hippocrepian lophophor, which bears a crown 

 of about eighteen tentacles — the number being always even ; 

 between this lophophor and the vascular lip is the crescentiform 

 opening of the mouth. The author would keep the genus 

 Phoronis as a form closely allied to the more normal Gephyrea 

 iiierinia, and compares the head of Phymosoma as seen from 

 above with a view of Phoronis. — On the spinning apparatus of the 

 geometric spiders, by C. Warburton (plate v.). Proves by a 

 series of interesting experiments that a spider's line does not 

 coiisist of many strands fused or woven together, but ordinarily 

 of two or four distinct threads ; the ground line of the spiral is 

 double only, and the two strands are bound together merely by 

 the viscid matter, which envelops them. — On the structure and 

 functions of the cerata or dorsal papillae in some Nudibranchiate 

 Mollusca, by Prof. W. A. Herdman (plates vi. to x.). In some 

 six genera of British Nudibranchs examined, Herdman found 

 that the dorsal papillae, "cerata" of Lankester, were of two 

 kinds — (i) those containing diverticula of the liver, as in the 

 cases of Eolis and Doto, (2) those which were essentially but 

 processes of the body-wall having no connection with the liver, 

 as in Tritonia, Ancula, and Dendronotus. In Doris there are 

 true branchiae and no cerata. In Ancula both branchiae and 

 cerata are present. In Tritonia and Dendronotus there are 

 cerata but no true branchise. In Doto and Eolis there are no 

 true branchiae. Morphologically all the forms of cerata are prob- 

 ably epipodial processes ; they are not of primary importance 

 either in respiration or in digestion, but give to the animals, by 

 their varied shape and colours, appearances which are in some 

 cases protective and mimetic, and in others conspicuous and 

 warning, as may be best suited to the individual surroundings 

 and mode of life. — Further observations on the histology of 

 striped muscle, by C. F'. Marshall (plate xi.). — On Chseto- 

 branchus, a new genus of Oligochaetous Chaetopoda, by Dr, A, G. 

 Bourne (plate xii. ). This remarkable worm was found in the 

 mud from a " tank " in Madras town ; it is furnished with a re- 

 markable series of branchial processes, dorso-laterally placed— 

 a pair to each of the anterior segments, commencing with the 

 second segment ; these processes completely surround a portion 

 of the dorsal setre bundles. The species has been named Cluxto- 

 braiicJnis seiiipcri. — On the presence of Ranvier's constrictions 

 in the spinal cord of Vertebrates, by Dr. W. T. Porter, of St. 

 Louis (plate xii. Hs).~A. note to the editor from Prof. Biitschli, 

 of Heidelberg, giving an account of his experimental imitation 

 of protoplasmic movements. These protoplasma-like streaming 

 properties of minute globules of a specially treated olive oil are 

 of extreme interest. 



American Journal of Science, May 1890.— Experiments with a 

 pendulum-electrometer, illustrating measurements of statical 

 electricity in absolute units, by Alfred M, Mayer. The ap- 

 ]iaratus described affords an inexpensive and ready means of 

 presenting clearly to a class the nature of measurements of 

 statical electricity in absolute units ; the instrument may be 

 made to measure to the .yV of a dyne, and a series of experi- 

 ments are given to show that it gives the law of inverse squares, 

 serves to determine the law of dissipation of an electric charge, 

 and that it allows measures to be made of electrical distribution 



NO. 1074, VOL. 42] 



on conductors and the determination of quantity and potential. 

 — On electric potential as measured by work, by the same 

 author. A graphical illustration is given of the fact that in the 

 case of two electrified spheres the potential function is a measure 

 of work.— An elementary proof of the earth's rigidity, by Geo. 

 F. Becker. It is proved that a simple strain spheroid affords 

 an approximation to the deformation of an elastic globe suffi- 

 ciently close to serve as a basis for Sir William Thomson's 

 demonstration of the rigidity of the earth ; the whole subject 

 also being presented in a clear and elementary manner. — On the 

 hornblende of St. Lawrence County, N.Y., and its gliding 

 planes, by George H. Williams. From the evidence brought 

 forward it is concluded that an alteration of the symbols for the 

 terminal planes of hornblende is necessary to show its analogy 

 to pyroxene ; and that this change must be made in accordance 

 with the assumption that the gliding plane, now called the 

 orthodome P^- (Toi) is the basal pinacoid OP (001) as suggested 

 by Tschermak in 1884. — Note on some secondary minerals of the 

 amphibole and pyroxene groups, by Whitman Cross, In the 

 course of the microscopical examination of some rocks from 

 Custer County, Colorado, the author has observed two peculiar 

 minerals of secondary origin, one an amphibole, and the other 

 a pyroxene, and now describes their unusual properties, relation- 

 ships, and mode of formation. — On spangolite, a new copper 

 mineral, by S. L. Penfield. The specimen examined consisted 

 of a rounded mass of impure cuprite mostly covered with 

 hexagonal crystals of the new mineral. A full description of the 

 habit, optical and physical properties, and chemical composition 

 of the crystals is given. — Archaean axes of Eastern North 

 America, by James D. Dana. The partly or wholly Archaean 

 ranges in New England and Canada parallel and to the east of 

 the Appalachian protaxis are described, and the geological im- 

 portance of the included troughs or basins pointed out. — On the 

 metamorphic strata of South-Eastem New York by Frederick 

 J. H. Merrill. — The radiant energy of a standard candle ; mass 

 of meteors, by C. C. Hutchins. The whole radiant energy of 

 the candle used was found to be I '23 x 10^ ergs per second, and 

 the radiant energy of the visible part 2*46 x 10" ergs per second. 

 The author also points out how such measures may be used to 

 determine the mass of meteors. — Meteoric iron from North 

 Carolina, by L. G. Eakins. — Distinctive characters of the order 

 Hallopoda, by O. C. Marsh. — Additional characters of the 

 Ceratopsidae, with notice of new Cretaceous Dinosaurs, by the 

 same author. 



Botanische Jahrbiicher, von A. Engler, vol. xi., contains the 

 following papers : — An essay on the biological relations of the 

 flower of Aconitum, by Dr. M. Kronfeld, He states that 

 Aconitttm is an excellent example of a flower adapted to a 

 certain insect, and that it is dependent upon Bombus for its 

 fertilization, a fact which is further borne out by a comparison 

 of the geographical area of the two, that of Aconitum being 

 entirely covered by the area of distribution of Bombus. — Dr. O. 

 Drude, on the principles of distinction of the formations of 

 vegetation ( Vegetationsforniationen) as illustrated by the flora 

 of Central Europe. — A description, by L. Wittmack, of the 

 plants belonging to the Bromeliacecc, collected by Herr F. C. 

 Lehmann in Guatemala, Costarica, Columbia, and Ecuador. — A 

 description of new species of Nyctaginaceae, by Dr. A. Heimerl, 

 with one plate. — A monographic sketch of the genus Helleborus, 

 by Dr. V. Schiffner, — A contribution to the knowledge of the 

 distribution of the Scotch fir in Northern Germany, in which it 

 is stated that on the mainland it extends north of the Elbe as a 

 native plant, only as far as a line connecting Rostock, Schwaan, 

 Giistrow, Wittenburg, and Geesthacht ; in North-West Germany 

 it is native only in the Upper Harz. — An anatomical investiga- 

 tion of the foliage leaves of the Arbutoideae and Vaccinoideae in 

 relation to their systematic grouping, and geographical distribu- 

 tion leads Dr. Franz Niedenzu to the following conclusions : 

 that the Arbuteae are the oldest type, and of them more especially 

 Arbutus and Arctous, while Arctostaphylos is more recent ; the 

 most recent group is the Tliibaudieic. These results are based 

 upon details of the glandular and other hairs, of the teeth of the 

 leaf, the epidermis and cuticle (130 pp. and 4 plates). — On the 

 influence of the mean direction of the wind on the vegetation in 

 the water, with references also to other phenomena of vegetation 

 which depend upon the direction of the wind in the Western 

 Baltic, by M. J. Klinge.— On a new Potentilla from Central 

 America, by Dr. K. Fritsch. — Contributions to the knowledge 

 of the Amaryllidaceae, by Dr. F. Pax. — A list of the wild plants 

 of the province of Wologda, by N, A. Ivanitzky. — On the 



