April -J, 1881] 



NA TURE 



545 



morpholo^ and systematic botany, with practical worl< in the 

 Botanical Gardens. 



The Demonstrator of Comparative Anatomy will take an 

 advanced class for instruction in the mammalia during the Easter 

 term. 



Prof. Stuart next term open^ his new workshops and drawing 

 office ; in the latter in-truction will be given in mechanical 

 drawing and in machine des'gning, and also in graphical r-taiics 

 and its application to the theory of structures. 



Mr. Garnett will commence an elementary course of lectures 

 on electricity and magnetism on May 2 in the chemical laboratory 

 of St. John's College. 



The Senate has approved of Lord Rayleigh'.s appointment of 

 two joint demonstrators of physics instead of one, and of the 

 payment of a stipend of too/, to each. 



Mr. Balfour will lecture on the embryology of aves and mam- 

 malia next term, and have a practical class in that subject. 



The Court of Assistants of the Haberdashers' Company have 

 have given to each of the schools under their management a 

 cabinet of minerals, purchased from the executors of the late 

 Prof. Tennant. The schools of the Company are at Monmouth, 

 Newport, Hatcham, and Hcxton. 



SCIENTIFIC SERIALS 



Annalen der Physik iind Chemie, No. 3. — Constants of elasti- 

 city of fluor-spar, by H. Klang. — On the source of beats and 

 beat -tones in harmonic intervals, by R. Koenig.- — Description of 

 a beat-tone apparatus for lecture experiments, by the same. — 

 Contribution to the theory of resonance, by F. Kulacek. — 

 Some applications of the law of disper-ion to transparent, semi- 

 tran-parent, and opaque media, by E. Ketteler. — Researches on 

 the spectra of gaseous bodies, by F. Lippich. — On the electro- 

 motive force of galvanic combinations formed of zinc, sulphuric 

 acid and platinum, or copper, silver, gold, or carbon, by C. 

 Fromme. — On a new form of the Topler mercury pump, and 

 some experiments made with it, by E. Bessel-Hagen. — Re- 

 searches on the height of the atmosphere and the constitution of 

 gaseous heavenly bodies (continued), by A. Ritter. — On abs.irp- 

 tion of solar radiation I y the carbonic acid of our atmosphere, 

 by E. Lecher. — On the idea of galvanic polarisation, by W. 

 Beetz. — On an artificially-formed body which takes polar direc- 

 tions and shows polar attractions, by W. Holtz. 



Zeitschrift fiir wissenschaftliche Zoologie, vol. xxxv. part 2, 

 February, 18S1. — Dr. H. Adler, on the alternation of generations 

 in the oak-gall insects, pp. 150-246, a very exhaustive treatise, 

 with two admirably-coloured plates of the galls and one of 

 the ovipositors, &c. , of the gall-insects. — Hans Virchow, on the 

 vessels in the eye and the appendages of the eyes in frogs, with 

 two plates. Elias Metschnikofif, researches on the Orthonectidas, 

 with a plate. — ^Jos. Th. Cattie, contribution to a kno>vledge of 

 the chorda supra-spinalis of the lepidoptera and of the central, 

 peripheral, and sympathetic nerve systems in caterpillars, with a 

 plate. — Dr. H. Bolau, on the pairing and propagation of a 

 species of the genus Scyllium. — N. Kleinenberg, on the origin of 

 the ova in Eudendrium (with a woodcut). 



SOCIETIES AND ACADEMIES 

 London 



Royal Society, March 24.— "Observations on the Locomo- 

 tive System of Echinodermata. " (The Croonian Lecture.) By 

 G. J. Romanes, M.A., F.R.S., and Prof. J. C. Ewart, M.D. 



The principal results had reference to the tube-systems and 

 nervous systems of the echinoderms. It was shown by injection 

 that the ambulacral system and the so-called blood-vascular sys- 

 tem are each closed systems, save at then- common origm in the 

 fnadreporic plate. Both systems communicate through this plate 

 writh the intemal medium, but the oue much more freely than 

 the other, the am'oulacral system being the least patent, so that 

 it Is only when a pressure of two feet is maintained for a number 

 of hours that the injected fluid slowly permeates the stone-canal, 

 or sand-tube, to ooze through the madreporic plate. Regarding 

 the nervous system, it was found in Echinus that lateral branches 

 arise from the five radial trunks to escape with the pedicels 

 through the apertures of the pore plates Each of these branches 

 then courses down the pedicel, with which it escapes to the ter- 

 minal sucker. From these lateral branches there also arises an 

 intimate nerve-plexus, which covers the whole external surface 



of the shell, lying almost immediately beneath the surface epi- 

 thelium, and extending from the shell to all the spines and 

 pedicellarire. In stained specimens the nerve-fibres and cells 

 were traced to the capsular muscles at the bases of the sjiines, 

 and delicate fibres were detected running up the spines and 

 pedicellarix, immediately below their epithelium. In the case 

 of the pe(ii';ellaria: it appeared from several preparations that 

 delicate fibres extended as far as the sensitive epithelial pod 

 situated on the inner .siu-face of each trident mandible, a short 

 distance from the apex. 



Such being the principal morphological results, the paper 

 went on to detail a number of physiological experiments. First 

 it was pointed out that the natural movements of echinodermata 

 exhibit a high degree of co-ordination. Thus, for instance, all 

 the echiuMclerms are able when inverted on a flat floor to right 

 themselves. The common starfish does this by twisting the 

 ends of two or more of its rays round, so as to bring the 

 terminal suckers into action upon the floor of the tank, and then 

 by a succtssive and similar action of the suckers further back in 

 the series the whole ray is progressively twisted round, so that 

 its ambulacral surface is applied flat against the floor. The rays 

 which perform this action twist their spirals in the same direc- 

 tion, and by this concerted action drag the disk and the remain- 

 ii.g rays over themselves as a fulcrum. Other species of starfish 

 which have not their ambulacral suckers sufficiently developed 

 to act in this way execute their righting movements by doubling 

 under two or three of their adjacent rays, and turning a somer- 

 sault over them, as in the previous case. Echinus rights itself 

 when placed on its aboral pole, by the successive action of two 

 or three adjacent rows of suckers — so gradually rising from 

 aboral pole to equator, and then as gradually falling from 

 equator to oral pole. Spatangus executes a similar manceuvre 

 entirely by the successive pushing and propping action of its 

 longer spines. 



Experiments in stimulation showed that 'all'the echinoderms 

 observed sought to escape from injury in a direct line from the 

 source of irritation. If two points of the surface are stimulated 

 the direction of escape is the diagonal between them. When 

 several points all round the animal are simultane'iu-ly stimulated 

 the direction of advance becomes uncertain, with a marked 

 tendency to rotation upon the vertical axis. If a short interval 

 of time be allowed to elapse between the application of two suc- 

 cessive stimuli the direction of advance will be in a straight line 

 from the timulus applied latest. If a circular band of injury 

 be quickly made all the way round the equator of echinus, the 

 animal crawls away from the broadest part of the band, i.e. from 

 the greatest amount of injury. 



The external nerve jjlexus supplies innervation to three sets of 

 organs — the pedicels, the spines, and the pedicellariEe ; for when 

 any part of the external surface of echinus is touched, all the 

 pedicels, spines, and pedicellari:c within reach of the point that 

 is touched imuiedately approximate and clo^e in upon the point, 

 so holding;- fast to whatever body may be used as the insii-ument 

 of stimulation. In executing this combined movement the pedi- 

 cellari^ are the most active, the spines somewhat slower, and the 

 pedicels very much slower. If the shape of the stimulating body 

 admits of it, the forceps of the pedicellariae seize the body and 

 hold it till the spines and pedicels come up to assist. 



And here we have proof of the function of the pedicellariae. 

 In climbing perpendicular or inclined surfaces of rock covered 

 with waving seaweeds it must be no small advantage to an 

 echinus to be provided on all sides with a multitude of forceps 

 adapted, as described, to the instantaneous grasping and arresting 

 of a passing frond ; for in this way not only is an immediate hold 

 obtamed, but a moving piece of seaweed is held steady till the 

 pedicels have time to establish a further and more permanent 

 hold upon it with their sucking disks. That this is the chief 

 function of the pedicellarias is iudicated by the facts that (l) if a 

 piece of seaweed is drawn over the surface of an echinus this 

 function may clearly be seen to be performed ; (2) that the won- 

 derfully tenacious grasp of the forceps is timed as to its duration 

 with an apparent reference to the requirements of the pedicels, 

 for after lasting about two minutes (which is about the time 

 required for the suckers to bend over and fix themselves to the 

 object held by the pedicellariae, if such should be a suitable one) 

 this wonderfully tenacious grasp is spontaneously released ; and 

 (3) that the most excitable part of the trident pedicellariae is the 

 inner surface of the mandibles, about a third of the "ay down 

 their serrated edges, i.e. the part which a moving body cannot 

 touch without being well within the grasp of the forceps. 



