BIOLOGICAL NOTES

THE SHINING Slave-Maker (Polyergus luciDUS).—The Rev. H. M'Cook is as fortunate as he is energetic in his studies of the American ants. At the December 1880, meeting of the Academy of Natural Sciences of Philadelphia he read a paper on the discovery at the foot of the Allegheny Mountains, near Altoona, of a nest of Polyergus lucidus, the American represen tative of the Legionary Ant of Huber (P. rufescens), an ant associated with that author's discovery of ant-nests, in which certain ants have associated with them, in a sort of slavery, ants of another species. The nest had four gates separated a few inches from each other; the chambers were placed one above the other, united by tubular galleries. In an inner ovoid chamber numbers of the ants, male and female, appeared; mingled with these in large numbers were workers in three forms-major, minor, and dwarf of Formica Schauffussi. A portion of the excavated nest was broken into, and on the next day but one was visited. None of the shining ants were at work, but the "slaves" were very busy cleaning out the galleries; a portion of the slaves were engaged in an extensive migration; a few were carrying their fellows, but for the most part the deportation was confined to the males and females of the shining ants. It was wonderful to see the large virgin-queens carried up the perpendicular face of the cutting for eighteen or twenty inches, and then for the distance of six feet over the ground and through the grass, and this in a few seconds over a minute. The shining ants are able to take a most wonderful grip. One of them had fallen under the displeasure of another, who held her firmly grasped by the middle thorax. Anxious to preserve the colony from unnecessary loss, Mr. M'Cook lifted the two out on the point of a quill toothpick, laid them on his hand, and thrust the fine point of the quill between the jaws of the agressor, and so teased her that she released her fellow. The rescued ant instantly clasped the palm of his hand, threw her abdomen under her, and then, with back curved like that of an angry cat, sawed and tugged away at the skin until an abrasion was made. The other ant still clung fast by her mandibles only to the toothpick's point, her body stretched out into space, her limbs stretched outwards, except one hind leg, which was a little bent upward, and thus without any perceptible support except that which her jaws gave her upon the quill-point, she hung outstretched for several minutes. About a month after its discovery the nest was again visited; it was abundantly peopled; the winged forms of the shining ant were however gone. Having succeeded in colonising these ants Mr. M'Cook was able to confirm in many particulars the statements of Huber, Forel, and others, but he never hap: pened to see the slaves feeding their masters. He noticed that they seemed to like to move towards both warmth and light, but he does not seem to have settled the question whether they would not prefer the warmth without the light. They would appear to be very clean in their ways and persons. Various experiments seemed to establish the fact that these slave-makers always keep a guard ready at once for any attack.

ON THE RED COLOUR OF SALT COD.-During the hot and damp weather of summer in the United States the dried codfish sometimes exhibit a peculiar redness of colour. These red fish, as is well known, putrefy comparatively quickly, and this fact, taken in connection with the disagreeable, and in such fish unusual, colour, renders them unfit for market, so that in seasons when the redness prevails dealers in codfish suffer often very considerable losses. Prof. Farlow, M.D., was requested by the United States Fish Commission to investigate this subject, and his report appears in the Fish Report for 1880. In September, 1878, he went to Gloucester to examine the fish stores. The weather was at that time hot and damp, and the codfish then being prepared for the market were largely affected by the redness. This redness disappears with the return of cool weather. In most cases it does not appear until the fish have been landed from the vessels, though in a few cases the colour has appeared in the stock while still on board. A microscopical examination showed that the redness was owing to a very minute plant, Clathrocystis roseo-persicina, a species known to be closely related to C. aruginosa, so common in fresh-water ponds, and which has lately come into public notice in the States in consequence of the so called pig pen odour which it exhales when decaying. This red species is known both in America and Europe, and has been recently investigated by Cohn and others. It may sometimes be found tinging the surface of damp ground with a purplish tinge, and the anatomist is not unfamiliar with it as

growing in his macerating tubs. It would appear not to flourish or increase very rapidly at a temperature below 65° Fahr. How it got to attack the dried fish was the next question. It was found that the plants could come from many sources, for it was found present in quantities in the wood-work of the wharves and packing-stores, but above all Prof. Farlow detected it in the salt with which the fish were cured. The salt from Cadiz had even a slight rose tinge. It will be a matter of interest, which perhaps some of our readers may help to solve, as to whether this plant is known in European fish-stations. In the great Norwegian cod-fisheries the temperature may not be high enough to favour its growth. As remedies Prof. Farlow suggests care in the selection of salt, and the constant cleaning of all wood-work or vessels that may come in contact with the fish. In addition to the red alga small quantities of cells destitute of colouringmatter and arranged in fours were not unfrequently found in the infected cod-fish. These suggested the genus Sarcina, but were not S. ventriculi. They rather, except in the absence of colouring-matter, resembled Glaocapsa crepidinum, Thuret, which species is common enough on the wood-work of the Gloucester wharves. While there is this resemblance Prof. Farlow prefers for the moment, and pending further investigation, to call it a Sarcina, and to describe it as a new species (S.? morrhuæ).

The

MARINE ISOPODS OF NEW ENGLAND.-One of the most remarkable papers forming the extensive series of appendices to the Report of the United States Commissioners of Fish and Fisheries for 1878 is perhaps that by O car Harger on the marine Isopods of New England and adjacent waters. limits chosen commence at Nova Scotia to the north and extend southwards to New Jersey. Forty-six species are recorded, and figures of these with the requisite details of anatomy are given on thirteen plate; several new species and one new genus (Syscenus) are described. It will be noted that the number of species is very considerably less than that known to frequent the British coasts, and of the former only eight are identical with British forms. This difference is very marked in the genus Sphæroma, of which genus there is but one species native to New England, while Bate and Westwood describe a dozen species belonging to this family as natives of Britain. Limnoria lignosum, one of the most destructive of the group, is apparently as common on the American coasts as on our own shores. It does not usually occur much below high-water mark, though Prof. Verrill has found it at a depth of ten fathoms in Casco Bay, and it was dredged by the U.S. Fish Commission at a depth of 7 fathoms in Cape Cod Bay, Massachusetts. species has been found around the British Islands, three species Of the family of the Cymothoida, of which we believe as yet no belonging to three different genera are in Mr. Harger's list.-To this memoir there is appended a very complete list of authorities and an alphabetical index.

STATISTICS OF DISEASE IN ITALY.-In a recent paper to the Lombard Institute, Prof. Sangalli gives statistics of the diseases which terminated fatally in the Civic Hospital of Pavia during the period 1855 to 1881. The material was 6644 bodies which came up for autopsy, and the causes of death were, in decreasing order, genuine inflammation, 4504 deaths; tuberculosis, 808; pyæmia, 337; cancer, 366; hepatic cirrhosis, 252; extravasation of blood in the brain, 254; chronic ulcer (gastric and duodenal), 72, &c. (there being 2140 deaths apart from those by true inflammation). The 4504 deaths from inflammation presented 7962 separate inflammations. The deaths from tuberculosis are seen to be about 12 per cent. The ages most exposed to that disease lie between 20 and 30; next come those between 10 and 20, and between 30 and 40, about equal. There were twelve cases between 70 and 80, and one in an old man of 84. It does not appear that one sex suffers more than the other. Cancer occurs most between 50 and 60, and most largely in liver, lymphatic glands, and stomach. The patients were largely of the peasant class, and the author cannot support Niemeyer's view, that people living in marshy districts, liable to malaria, have a certain immunity from tuberculosis. Nor do the figures confirm the asserted tendency of ulcer in the stomach to favour the development of tuberculosis. Pyæmia appeared mostly in the lungs (149 cases out of 470), pleura, 99; liver, 73, &c. some years there was a remarkable diminution of this disorder.

In

THE EYE AND INTENSITY OF COLOUR.-With an apparatus consisting of two Nicols with a gypsum plate between, and a spectroscope with a third Nicol attached to the eye-piece, Herr Dobrowolsky has examined the sensibility of the eye to spectral

colours with different intensities of light (Pfluger's Archiv, v. 24, p. 189). From a large number of measurements it was found that, on an average, the red-colour sensation first occurred with a light-quantity equal to 23, while for blue the lowest amount of light was. Thus blue gives a sensation with an amount of light sixteen times less than that required for red. With rise in the degree of brightness, the increase of sensibility to red proceeds pretty regularly; but for blue the increase becomes gradually greater (with the weakest degrees of brightness this increase was = O'22, with the strongest o 82, with the mean o'36). Comparing the two sensibilities together, from the maximum of light strength to the minimum, the sensibility to blue is always found to exceed that to red (maximum thirteen and a half times, minimum sixteen times, mean four times).

ISOETES LACUSTRIS.-In an interesting paper read before the Academy of Sciences of Paris (January 10, 1881), M. E. Mer calls attention to the peculiar conditions under which different forms of this fresh-water plant seem to originate in the Lake of Longemer. The basin of this lake was once occupied by a glacier, and now presents several different sorts of bottom. The soil to a depth of two to three metres is composed in part of a gravel formed of rock débris united by an iron cement, in part of ancient moraines, or where near the surface these will be mixed with the remains of plants and form a pretty tenacious mud. In all these situations Isoetes is to be found, but the plants differ most remarkably both as to their form, their structure, and their mode of reproduction as they are found in the different habitats. Taking the leaf-development as a guide, four varieties are easily discerned :-(1) humilis, growing sparsely in the gravel and sterile shallows, the leaves are not only few in number, but always of diminutive dimensions; sporange generally wanting or represented by a small cellular mass which rarely ever forms a propagule, and then these with puny leaves; (2) stricta, found on the borders of the lake or in the old alluvial, therefore in less sterile quarters than the preceding; leaves more numerous, stout, but still of small size; (3) intermedia, growing on ground formed of a mixture of mud and clay, either on the borders of the lake or at a depth of from one to two metres, leaves quite intermediate in character between the previous variety and the next; (4) elatior, growing on the clayey depths, with long leaves. The first form is always found isolated, and as to its asexual reproduction there is nothing more to be said; but the other three, according as they are subject to more or less heat, present each three varieties characterised by the mode of reproduction. I. Sporifera, isolated individuals, mostly furnished with well-developed sporangia, stem large, roots numerous, leaves large. 2. Gemmifera, few fertile sporangia, but most of the leaves are furnished with propagula, and these well furnished with leaves, generally dextral, stem fairly developed. 3. Sterilis, individuals growing in compact masses, stems and roots slender, leaves not numerous, long and narrow, fertile sporangia very rare, and more often undeveloped masses of cells or abortive propagula. It would seem as if these facts had a practical interest to the collector, who may find in them a guide as to where to look for fertile specimens.

GEOGRAPHICAL NOTES

On Friday, April 1, the French Geographical Society held a meeting in the large hall of the Sorbonne for the reception of Dr. Lenz on his return from Timbuctoo. M. Milne-Edwards was in the chair. Dr. Lenz, as our readers know, has been very successful, although his conclusions are adverse to the construction of a railway from the Niger to Algeria throughout the Sahara. On the following morning the Society received a telegram stating that Col. Flatters had been murdered by Touaregs at some distance from the Lebhkha Amagdor. In the evening the sad news was confirmed by an official message, stating that four starving Arabs from the mission had arrived at Ouargla, and that the Khobfa had left with four hundred mehari and camel horsemen to rescue the survivors, who were besieged south of Messaguer in the Touat region proper. Happily the news of the disaster to Col. Flatters' expedition has not yet been further confirmed, and authorities in Paris are inclined to believe that it has been much exaggerated, and that the story of the four natives has many elements of suspicion about it.

DR. LENZ, in his lecture at Paris, gave some interesting details on the present condition of Timbuctoo. Its houses are built of brick, and the population is now only 20,000. It has greatly

decayed, and the inhabited part of the town is surrounded by great spaces covered with ruins. There are numerous schools and rich libraries. Dr. Lenz had a cordial reception, and every night during his twenty days' stay he was present at religious conferences which the learned men of the city held with his interpreter; the commentaries on the Koran formed the only subject of conversation. Timbuctoo is united with the Niger, six miles off, by a series of lakes, formerly canals. Dr. Lenz has also made some interesting observations on the Sahara, tending to confirm the conclusions of Rholfs and other recent scientific travellers as to the variety which is to be met with in the great desert. It is really a plateau about 300 metres in altitude, no part of it being below the level of the sea. Granite hills, sandy plains, shallow lakes, fertile oases, alternate over nearly the whole surface, while beasts of prey are rarely to be met with. Dr. Lenz will contribute a full account of his journey to the Berlin Africa Society, in whose journal many of his letters have already appeared.

It is with sincere regret that we record the death of Lieut. Karl Weyprecht, at the age of forty-three, on March 29, of consumption. Lieut. Weyprecht will be known to our readers as the discoverer, with Lieut. Payr of Franz-Josef Land, in the Austro-Hungarian Expedition of 1872-4. His observations on the aurora borealis were of especial value, and he has published several papers on the subject. He was also the originator of the scheme for establishing a series of international observations around the Pole, which is likely to be realised next year.

THE Rev. G. Brown, the well-known representative of the church militant in the South Pacific, contributes to the new number of the Geographical Society's Proceedings a paper descriptive of a recent journey which he has made along the coasts of New Ireland and the adjacent islands, the latter including Sandwich Island, Portland Islands, and New Hanover. Dr. Benjamin Bradshaw, who has spent some years in collecting natural history specimens in the Upper Zambesi region, also contributes a brief paper on the Chobe River, together with a sketch-map of a portion of its course, adding materially to our knowledge of the geography of this region. Mr. Crocker's paper on Sarawak and Northern Borneo, lately read before the Society, is also given, and is illustrated with a good map. The geographical notes are full of interesting matter, one giving an account, by Mr. Sibiriakoff himself, of the voyage of the Oscar Dickson to the Yenisei Gulf in 1880. Another furnishes conclusive proof of the usefulness of the course of scientific instruction provided by the Council for intending travellers in foreign countries. From the last note we learn that Mr. C. R. Markham, the indefatigable secretary, is preparing for the forthcoming volume of the Journal a sketch of the Society's work in the past fifty years.

IN the current number of Les Missions Catholiques, Père

Richard, a missionary in Algeria, commences an account of his journey, in company with Père Kermaben, among the Tuareg. Azguer tribes of the Sahara. The object of their journey was to study this almost unknown region, and to cultivate friendly relations with the chiefs and people generally with a view to the formation of a missionary station. The more interest attaches to Père Richard's narrative, as it deals with the very region which Col. Flatters has been now exploring with the object of settling the best practicable route for the projected Trans-Sahara railway. An entirely new map of this part of Africa, based on Père Richard's notes, accompanies the number.

A LATELY-ISSUED batch of Reports from H. M. Consuls (Part vi. of last year) contains useful geographical information respecting portions of South America, that relating to Chili and Peru being specially interesting at the present moment.

UNIVERSITY AND EDUCATIONAL
INTELLIGENCE

CAMBRIDGE.-On the 31st inst. the honorary degree of LL.D. was conferred on Prof. Helmholtz of Berlin at a special congregation.

Prof. Humphrey will take his usual May classes for the second M. B. and Natural Sciences Tripos next term, and the demonstrator will give demonstrations of the organs.

Prof. Babington will lecture on botany four times a week next term, beginning April 26. Mr. Hillhouse will give lectures on

morphology and systematic botany, with practical work 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 opens his new workshops and drawing office; in the latter instruction will be given in mechanical drawing and in machine designing, and also in graphical statics 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 100l. to each.

Mr. Balfour will lecture on the embryology of aves and mammalia 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 Hoxton.

SCIENTIFIC SERIALS

Annalen der Physik und Chemie, No. 3.-Constants of elasticity 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. Kolacek.Some applications of the law of dispersion to transparent, semitransparent, and opaque media, by E. Ketteler.-Researches on the spectra of gaseous bodies, by F. Lippich.-On the electromotive 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 Töpler mercury pump, and some experiments made with it, by E. Bessel-Hagen.-Researches on the height of the atmosphere and the constitution of gaseous heavenly bodies (continued), by A. Ritter.-On absorption of solar radiation by 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 directions and shows polar attractions, by W. Holtz.

Zeitschrift für wissenschaftliche Zoologie, vol. xxxv. part 2, February, 1881.-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 Metschnikoff, researches on the Orthonectidæ, with a plate.-Jos. Th. Cattie, contribution to a knowledge 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 Locomotive 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 system are each closed systems, save at their common origin in the madreporic plate. Both systems communicate through this plate with the internal medium, but the one much more freely than the other, the ambulacral 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 terminal sncker. 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 epithelium, and extending from the shell to all the spines and pedicellariæ. In stained specimens the nerve-fibres and cells were traced to the capsular muscles at the bases of the spines, and delicate fibres were detected running up the spines and pedicellariæ, immediately below their epithelium. In the case of the pedicellariæ it appeared from several preparations that delicate fibres extended as far as the sensitive epithelial pod situated on the inner surface 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 echinoderms 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 successive 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 direction, and by this concerted action drag the disk and the remain. ing 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 manoeuvre 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 simultaneously 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 successive stimuli the direction of advance will be in a straight line from the stimulus 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 plexus supplies innervation to three sets of organs-the pedicels, the spines, and the pedicellariæ; for when any part of the external surface of echinus is touched, all the pedicels, spines, and pedicellariæ within reach of the point that is touched immediately approximate and close in upon the point, so holding fast to whatever body may be used as the instrument of stimulation. In executing this combined movement the pedicellariæ 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 pedicellariæ 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 pedicellariæ. 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 no only is an immediate hold obtained, 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 pedicellaria is indicated by the facts that (1) 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 wonderfully 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 pedicellariæ, if such should be a suitable one) this wonderfully tenacious grasp is spontaneously released; and (3) that the most excitable part of the trident pedicellaria is the inner surface of the mandibles, about a third of the way down their serrated edges, i.e. the part which a moving body cannot touch without being well within the grasp of the forceps.

Removing the pentagonal nerve-ring has no effect at all upon the pedicellariæ 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 permanently destroyed-their bristling movements no longer serving to convey the animal from a source of irritation, but only causing the animal 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 continuing 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, everywhere 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 congratulated the Society on its flourishing condition. At no period in its history 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 discoveries of the year. The supposed decomposition of chlorine and iodine by Victor Meyer has been found to be capable of another explanation. The solar and stellar evidence of the decomposition of metals accumulated by Mr. Lockyer has 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 lost by death ten Fellows, includ ing Sir B. Brodie, Dr. Stenhouse, Prof. W. H. Miller, 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 were received and adopted, and the Officers and Council elected for the ensuing year. President, H. E. Roscoe. Vice-Presidents : F. A. Abel, Warren De La Rue, E. Frankland, J. H. Gladstone, A. W. Hofmann, W. Odling, Lyon Playfair, A. W. Williamson, A. Crum Brown, J. Dewar, J. H. Gilbert, A. V. Harcourt, J. E. Reynolds, J. Young. Secretaries: W. H. Perkin, H. E. Armstrong. Foreign Secretary, Hugo Müller. 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 Moser read a paper on electrostatic induction, especially relating to the branching of the induction in the differential inductometer and in the electrophorus. The author's experiments bore out the hypothesis of induction as enunciated by Faraday. Prof. Ayrton suggested the importance of adding guard-rings to the small plates of the five-plate inductometer 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.-Prof. Reinold, one of the secretaries of the Society, read a paper by himself and Prof. Rückert on the electrical resistance of liquid films with a revision of Newton's scale of colours. The experiments were in continuation of those published by the authors in 1877. Their object was to determine whether a film thinning under the action of gravity gave any evidence, by a change in its specific resistance, of an approach to a thickness equal to twice the radius of molecular attraction, and also to devise a method of finding the amount of water which might be absorbed by or evaporated from it. The thickness of the films was determined from their colour by means of two beams reflected from different mirrors on them.-Newton's scale of colours was revised by observations on Newton's rings, and partly by more than 2000 observations on the rings them

in the same circuit.

selves. The thicknesses determined by direct observations on Newton's rings and those in the corrected table rarely differ by 1 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, with a little nitrate of potash added to increase their electric conductivity. They were blown in a glass case 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 blotting-paper, the lower 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 with 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 potential above and below a known resistance placed The specific resistance of the liquid from which the films were formed was 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 great 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 resistance of the film agree with that of the Hquid 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 diameter 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 hygrometric 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 Dutton and Capt. George Ernest A. Ross were elected Fellows of the Society.-The following 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 exposed 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 Plastremys lata. The presence of these freshwater 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 described 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 fossiliferous zone 4 feet in thickness, containing Ammonites inflatus, A. auritus, and species of Ponopea, Cucullæa, Arca, and Trigonia, and immediately below this a separate band containing an undetermined 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 surmounted by 5 feet of freestone. The latter contains Ammonites rostratus, and the cherts various fossils, chiefly bivalves. Clathraria Lyelli also occurs at this level. Above the greensands come 6 feet of chloritic marl: the upper 3 feet fossiliferous, with a base of hard phosphatic nodules containing crushed specimens of Pecten asper; the lower 24 feet compact, with darker grains and few fossils. The author compared the sections of