strain on the resources of the Dogger Bank. Dr. Masterman and others advocated the attacking of special problems, and thought that the more general questions might be for the present postponed. Systematic Study of Oceanic Plankton. Dr. G. H. Fowler put forward some suggestions for the more systematic study of oceanic plankton. Evidence that temperature appears to be the chief determinant in the distribution of plankton was cited, the highest depth of a species being the position of its maximum, the lowest depth that of its minimum, temperature at any given geographical position. It was urged that, for the solution of the problems demanding attention, oceanic expeditions should be confined to the systematic study of small areas instead of making long voyages, that the upper zones of water should be more carefully investigated than has hitherto been the case, and that standard tow-nets should be adopted internationally by all expeditions in order to afford means of comparison of the fauna in different seas and under different conditions. Life Cycle of the Protozoa. Prof. Calkins referred to some features in the life cycle of the Protozoa, and urged that the whole life cycle should be worked out before a new species could be regarded as safely established. This safeguard would prevent confusion and the undue multiplication of species. Prof. Calkins showed, for example, that two such well-known and apparently fixed species as Paramoecium caudatum and aurelia are no longer to be regarded as distinct. During the progress of a culture of P. caudatum, an individual appeared with all the characters of P. aurelia (including form of body and double micronuclei), but after forty-five generations, the organisms being watched daily, the aurelia characters were lost, and the entire race became P. caudatum again. In any such life cycle the organisms pass through phases of vitality comparable to the different age-periods of Metazoa. There are periods of (1) youth, characterised by great vigour of cell multiplication; (2) maturity, indicated by changes in the chemical and physical balance of the cell, accompanied by differences in size or protoplasmic structure, leading to the formation of conjugating individuals, with or without sexual differentiation; (3) in forms which do not conjugate, old age or senescence, ending in death. In many forms, especially where dimorphic gametes are produced, the period of sexual maturity leads directly to that of old age, and gametes which fail to conjugate soon die without further multiplication, as in the majority of Sporozoa and in many Rhizopods. In Ciliata, although failure to conjugate is finally fatal, many generations may be formed before death occurs, and in these may be studied the peculiar cytoplasmic changes which accompany protoplasmic senility. While working at the maturation phenomena in Paramecium, Prof. Calkins and Miss Cull were able to show that the curious crescent form assumed by the micronucleus is the stage of synapsis, the chromosomes being double at this time, apparently by union side by side in typical parasynapsis. The two following maturation divisions have not yet, however, been completely followed. The speaker also dealt with the subjects of fertilisation and parthenogenesis, pointing out that the latter has only a limited success, acting merely to postpone or counteract physiological death (Hertwig). Physiological and germinal death in Protozoa are connected with exhaustion of vitality and of definite substances in the cell. Infection of Monkeys with Guinea-worm. Dr. R. T. Leiper described some results obtained by the infection of monkeys with guinea-worm. These confirm the view that Filaria medinensis gains access to the human host by introduction in the larval stage (while still contained within its intermediate host, Cyclops) into the stomach in drinking water. The larvæ are released and stimulated into activity by the gastric juice. A monkey which had been infected in this way was killed after six months, and five guinea-worms-three unfertilised females and two males (each of the latter 22 mm. long)-were found. No experimental evidence could be obtained in support of the theory which has, during recent years, been Mr. Arnold T. Watson gave an account of the habits of tube-building worms. He showed how Sabella collects, by means of its branchial tentacles, particles which are applied by means of the collar lobes to the outside of a mucous tube secreted by the epidermis. As a safeguard against the intrusion of an enemy, the mouth of the tube usually collapses when the worm retracts, but in one of the rock-boring species the end of the tube rolls up like the frond of a fern. Terebella builds its tubes of sand. shells, or gravel, terminated by an arborescent arrangement composed of single grains of sand or other suitable material. Pectinaria produces the well-known conical sand-tubes, the material for which is selected with great care. Owenia constructs a flexible tube by attaching in an imbricating manner flat sand grains and fragments of shell to a membranous tube secreted by special epidermal glands. Panthalis weaves a massive tube composed of threads supplied by the parapodial glands. These tubes are open at both ends, but the worm is defended from attack by a series of internal valves at each end of the tube, which are automatically closed by the inrush of sea water immediately the inmate of the tube retracts itself. Papers on Lepidoptera. Prof. E. B. Poulton exhibited a series of forms of Acraca johnstoni, Godm., showing that each one of the protean series of varieties has been evolved in relation to a Ďanaine or Acræine model, the models and mimics occurring together on the slopes of Kilimanjaro. Dr. F. A. Dixey exhibited butterflies, some possessing an epigamic scent, others an aposematic or warning scent. and others in which both kinds of scent existed independently. It is well known that the male of Ganoris napi, one of our common white butterflies, exhales a fragrant scent (compared to that of lemon verbena) which is probably epigamic in significance. Dr. Dixey has found similar, though weaker, scents in the males of other British Pierina, Satyrinæ, and Lycænidæ, and many of the native African species were also found to possess an agreeable odour suggestive of chocolate, vanilla, or the scents of various flowers. These scents are generally distributed by specialised scales (androconia), the distribution being, to some extent, under control, the perfume being economised when not needed in courtship. The offensive odours are more or less shared by both sexes, but are sometimes stronger in the female, and generally occur in forms which on independent grounds, are believed to be protected. These aposematic odours are usually perceptible even in uninjured specimens, but are much more evident when the thorax is crushed. Mr. G. T. Porritt read a paper, full of details, on melanism in Lepidoptera. He pointed out that melani-m had increased with extraordinary rapidity in south-west Yorkshire and parts of Lancashire, and also occurred, to a less extent, in other parts of the United Kingdom. In some cases (e.g. Amphidasys betularia, Odontoptera bidentata) the change has been sudden, but in most cases there has been a gradual, though rapid, change from pale to black. More than thirty species are melanic in Yorkshire, most of which have become so during recent years. and there are other species which are tending in the same direction. Many of these melanic forms will probably, a no distant date, oust the ordinary pale forms. The variety varleyata of Abraxas grossulariata has, however, not increased, and, though known more than forty years ago, i as rare now as it was then, although melanism is a strongly impressed on the race that a brood reared this year, from a pair of moths from wild larvæ, were all o the extreme dark form, no single example showing an tendency towards the pale ordinary form. The reasons for and causes of the phenomenon were then discussed. T usually accepted theory is that the darker colour renders the insects less conspicuous as they rest upon the darkened (by soot, moisture, &c.) tree trunks, and, therefore, meer likely to survive and to perpetuate dark forms. Mr. Porritt did not believe that birds fed to any great extent on moths, and when they did they took them on the wing at night, when their colour similarity to trees would be of no service. Moreover, many melanic species do not affect tree trunks, e.g. Larentia multistrigaria, in which melanism has rapidly developed for no apparent reason. The theory that smoke and humidity in the manufacturing districts have caused melanism, although offering in many cases a likely explanation, seems to be rendered untenable by numerous exceptions. Mr. Doncaster remarked that melanism could not be explained as due to natural selection or as the result of external conditions, as the black forms in some cases arose suddenly, and quickly became numerous. The black form is dominant, that is, the offspring of a pair, one black and one pale, have a tendency to be dark. Dr. Dixey pointed out that in Pierines dark pigment is often substituted for light, the female being usually darker. There may even be two grades of colour in the females, a darker in the individuals found in the wet season, and a lighter in those found in the dry season. He considered that locality, altitude, and other conditions may have an influence in darkening the pigment. Pineal Eye of Geotria and Sphenodon. Prof. Dendy described the structure of the pineal eye of the New Zealand lamprey (Geotria), which agrees in most respects with that of Petromyzon, but the former is more complex in histological structure, its pigment cells being divided into inner and outer segments. The pineal nerve is connected both with the right habenular ganglion and the posterior commissure, and in all probability with Reissner's fibre, whereby it would become linked with the optic reflex apparatus described by Sargent. Prof. Dendy also directed attention to some newly observed details of structure in the adult pineal eye of Sphenodon. The rods of the retina project into the cavity of the eye, and are connected with a network of fibres, which is also connected with the "lens." The lens contains a large central cell which resembles a unipolar ganglion cell. Prof. Dendy concluded that, in both Geotria and Sphenodon, the pineal eye is a functional organ. Formation of Nucleoli. Prof. Havet (Louvain) traced the formation of true nucleoli or plasmosomes in the nerve cells and blood cells of Rana and Alytes. The central part of each is formed from a small, clear area situated in the centre of the telophasic figure, while the peripheral part is derived from the internal extremities of the chromosomes which remain when the rest of the chromosomes form the nuclear network. Occasionally chromosomes also become included in the central area, giving rise there to one or two chromatic structures. Milk Dentition of the Primitive Elephant. Dr. C. W. Andrews, in the course of a paper on the milk dentition of the primitive elephant, pointed out that in recent elephants, owing to the large size of the molars and the shortening of the jaws, the teeth have an almost horizontal succession, their manner of replacement differing widely from the vertical succession found in other mammals. But as the earlier relatives of the elephant are followed back through the various Tertiary horizons a gradual approximation to the ordinary mammalian type of tooth replacement is observed, until in the recently discovered Eocene Palæomastodon a form is reached in which the milk molars are replaced in the normal way by premolars, which, along with the permanent molars, remain in use throughout the life of the animal. A New Conception of Segregation. Mr. A. D. Darbishire directed attention to some essential but usually unrecognised features of the Mendelian theory. He pointed out that although half the total number of children born to hybrids were unlike their parents, the hybrids, according to that theory, bore no single germ cell containing an element representing an animal like themselves, and that if a hybrid could be made to multiply parthenogenetically it would produce no offspring like itself. An experiment for testing this theory in an individual case was described. Mr. J. T. Cunningham spoke on the evolution of the cock's comb; Mr. H. M. Bernard, on a periodic law in organic evolution, with a re-estimation of the cell; and Dr. H. J. Fleure and Miss Galloway gave a detailed paper on the habits of the Galatheidæ in relation to their structure; but these and a few other papers do not lend themselves to the purposes of a summary. J. H. ASHWORTH. THE ROYAL PHOTOGRAPHIC SOCIETY'S ANNUAL EXHIBITION. THIS exhibition at the New Gallery in Regent Street will remain open until October 27. The three rooms, the central court, and the balcony, indicate its five main divisions. The last of these is devoted to scientific and technical photography and its application to processes of reproduction, and the exhibits here naturally fall into three sections, namely, the ordinary exhibits, those contributed by special invitation of the council of the society, and a small collection of photographs that have no other interest than that they are good technical work, and represent subjects of or less interest, chiefly architectural. We hope to see this kind of work more fully represented in future exhibitions, for between the more strictly technical and the ultra-pictorial it has been almost squeezed more out of existence. A series of beautifully made models of light-pencils, which show the various effects of aberrations that particularly concern photographic lenses, is shown by Mr. C. Welborne Piper, and has been awarded a medal. The three dozen models illustrate very clearly a subject that must always be a somewhat difficult one. Immediately following this are a large number of photographs of living things, but chiefly birds, which appear to be receiving a very undue share of attention just now. Of these, we notice particularly a series of twenty-four photographs of the stone curlew in different stages of its existence, by Mr. W. Farren. Of the other subjects, "A Study of Wych Elms," by Mr. Alfred W. Dennis, is among the more novel. It is a series of seven photographs that show the same pair of trees, leafless and in leaf, and on larger scales the details of the trunk, blossom, fruit, leaves, and winter buds. Dr. Vaughan Cornish sends a further series of waves; Mr. J. C. Burrow two coal-mine subjects, excellently rendered as usual; and Mr. Bagot Molesworth a telephotograph of Vesuvius in eruption, taken from a distance of eight miles. In the invitation section, Mr. Douglas English shows some examples of mimicry in British insects, and a particularly realistic effect is obtained in some of them by making the original carbon print with a green tissue, and staining the insects with dyes to represent their natural colours. The Royal Observatory, Greenwich, has contributed several of its recent results, including some of last year's solar eclipse. Mr. F. E. Baxandall (for Sir Norman Lockyer) also illustrates the eclipse, and sends photographs of two British stone circles that were erected some four thousand years ago as astronomical observatories. Series of cloud photographs are shown by Dr. W. J. S. Lockyer and Captain D. Wilson-Barker. Photographs illustrating the investigation of crimes, such as forgery and burglary, and the detection of the criminals, by Prof. R. A. Reiss, of Lausanne, will be of very general interest. Mr. K. J. Tarrant shows a series of thirty photographs of high-tension electrical discharges. Mr. Edgar Senior has continued his study of the Lippmann method of colour photography, and although the image generally shows no grain under the microscope, he has by special illumination got the surface to appear covered with discs of light, though what these indicate is not very clear. There are a few photographs in "natural colours," but nothing better than, if quite so good as, has already been shown. Messrs. Sanger-Shepherd and Co., by preparing a more rapid and red-sensitive plate and special colour filters, have made it possible to take the three negatives necessary for their method of colour photography in three seconds, including the time required for changing the plates and light filters, when the light is only moderate and the lens aperture f/16. In the central court, besides a great deal of apparatus and several demonstrations of processes, the Adhesive Dry Mounting Co. shows its method of mounting by warm pressure. The Ozotype Co. shows in the north room several examples of "ozobrome prints. These are quite a new departure, a carbon print being produced by means of a bromide print without exposure to light, the silver image in the bromide print reducing the bichromate in the carbon tissue by mere contact. The original bromide prints and the carbon copies are shown side by side. C. J. GEODETIC OPERATIONS IN SOUTH AFRICA. IT will be admitted that the Administration of Southern Rhodesia acted wisely in accepting the timely counsel which Sir David Gill brought under its consideration. Some ten years ago His Majesty's Astronomer at the Cape pointed out to Lord Grey, who then administered the government of the colony, the desirability of basing the land tenure on a properly established system of survey. The adoption of such a course would not only afford the means of supplying a sound and incontrovertible evidence of title to the possessor, but would protect the Government against the perpetration of fraud and tend to diminish future litigation. Sir David Gill does not hesitate to say that in Cape Colony large tracts of land have been stolen from the Government, either through the wilful shifting of beacon marks or from carelessness due to inadequate surveying. Sir David Gill did not lay any great stress upon the scientific value that necessarily attaches to accurate measurement conducted on a large scale; but this point was not neglected, and the work was planned so as to give the greatest assistance to economic requirements, and at the same time to forward scientific interests. The one purpose was effected by carrying a chain of triangles eastwards from Bulawayo, covering the most thickly populated and important parts of the country, the other by extending the chain north and south along the thirtieth meridian, so that it might form part of the great arc of meridian which it is proposed to extend from the south of Natal to the Mediterranean. The actual district surveyed extends from about 16° to 20° south latitude and from 28° to 31° east longitude. overcame. Sir David Gill sketches the history of the work accomplished in successive years, from which can be gathered something of the difficulties which Mr. Simms and his assistants encountered and Abnormally wet seasons, illness among the staff, the necessary burning of the grass and the rising of the smoke preventing the measurement of horizontal angles, loss of cattle, and in one instance the destruction of the theodolite, are a few of the troubles that beset those who attempted geodetic operations in an unsettled country; but, notwithstanding these drawbacks, there remained only three stations south of the Zambezi which were not fully connected with the scheme of triangulation proposed. As the work is extended northwards these stations will be occupied, and thus form a useful link in the two systems. A matter of great interest in the report from a scientific point of view consists in the critical examination of the Jäderin wires used in the measurement of the base lines. This apparently convenient form of measurement was, it is believed, adopted by the Russian geodesists in the work connected with the Spitsbergen base, but in this country the apparatus has not been submitted to any very thorough test, and figures for the first time on a large scale in the geodetic survey of South Africa. Two wires, one of steel and the other of brass, constitute a "pair," and, as a rule, were used in this form. Each wire is about 1.65 mm. in diameter, and is stretched by an accurate spring balance with a tension of 10 kilograms. The length of three pairs 1 Report of the Geodetic Survey of part of Southern Rhodesia executed by Mr Alexander Simms, Government Surveyor, under the direction of Sir David Gill, KCB, F.R.S., His Majesty's Astronomer at the Cape. Pp. xiv 146. (Cape Town, 1905.) was each 80 feet, but two others of 100 feet and 320 feet respectively were used in crossing streams and gulleys. Another form of the same apparatus, occasionally used. consisted of a wire of "invar" nickel-steel and a wire of another alloy having a coefficient of expansion about the same as that of brass. The absolute length of each of these pairs was determined by repeated comparisons with a base line So feet in length, measured with a standard bar apparatus; but even the length of this base could not be assumed to be constant. The partially decomposed quartzose slate beneath the piers which carried the fiducia marks appeared to change slightly in position, especially after rain, and the length of this base as measured in the wet and dry seasons differed by half a millimetre. Constam measurement with the bars removed any source of error from this cause, since the change of length between the beginning and end of a set of wire comparisons was practically insensible. But the real source of error in the use of the Jäderin wires lies in the fact that the ordinary steel and brass wires are liable to change of length, due to re-arrangement of the molecules of the constituent metals which takes place independent of temperature after these molecules have been violently disturbed. The tendency in all new drawn wireis to shorten, very markedly at first, and to diminish in amount as a more stable arrangement of the molecules is established. In a postscript, however, it is stated that, as the result of experiments conducted at the International Bureau of Weights and Measures, it is found possible b careful annealing and special mechanical treatment to render the arrangement of the constituent molecules of "invar" wires practically stable, and that such wires ear be used as standards. Such wires, however, are examined here. As an evidence of the change of length in the wires actually used, we may quote the following:The length of a standard pair, at a temperature when both components were of equal length, was found to be in April and May, 1898 ... 24382.07 mm 24381-84 not October and November, 1898 Two base lines were measured in the course of the work one of 11 miles and the other of 13 miles. The first known as the Inseza base, was measured in three sections. the second in seven, each section being measured in oppsite directions. As an indication of the accuracy attained we give the repeated measures in the shorter base : Ть THE celebration of the four hundredth anniversary the foundation of the University of Aberdeen began c Tuesday, and will continue for several days. The co memoration has been planned on a magnificent scale, and the arrangements have been perfectly organised. formal proceedings opened on Tuesday morning with service at King's College in commemoration of the founding of the University by Bishop Elphinstone. In the afternoon, at a reception given by the Chancellor (Lor Strathcona) and other high officers of the University, th delegates of the British, colonial, and foreign universities were presented to the Chancellor and delivered their addresses. In the evening a banquet was given by t Lord Provost and the corporation. Among the distinguished foreigners who are taking part in the celebrations are:-Prof. H. Becquerel, Prof. Behring, Dr. C. N Candolle, Prof. Deissmann, Prof. Yves Delage, Dr. Anton Dohrn, Prof. A. Giard, Prof. H. Höffding, Prof. F. Hueppe, Prof. Jensen, Prof. Lombroso, Prof. Matsumura, Prof. Mendeléeff, Prof. Menschutkin, Prof. Hugo Münsterberg, Prof. W. Ostwald, Prof. Giuseppe Veronese, Prof. Paul Vinogradoff, Prof. J. W. Wijhe, and Prof. Weichselbaum. The lecture-rooms, laboratories, and other buildings which will be opened by the King to-day have cost more than 200,000l. to erect and equip. The new block completes the quadrangle, and includes new class-rooms and laboratories for physiology, geology, and agriculture; new rooms for education, medicine, modern languages, and other subjects; a new library for scientific literature, and new offices. We hope to give in our next number a description of this extension of the University, and an account of the brilliant ceremonies with which it has been Inaugurated. THE next session of the South-Eastern Agricultural College, Wye, will commence on October 1, and the inaugural address will be delivered by Dr. H. E. Armstrong, F.R.S., on October 2. A conference of fruit growers will be held at the college on October 22, when discussions on methods of planting, fungus diseases, insect attacks, strawberry culture, will be opened by Messrs. S. U. Pickering, F.R.S., E. C. Salmon, F. V. Theobald, and W. P. Wright. The chair will be taken by Mr. Laurence Hardy, M.P. Those wishing to attend the conference should send their names to the principal of the college. ON October 11 Sir William Anson will distribute the prizes awarded to students in the evening classes of the Royal Technical Institute, Salford. The calendar of the institute for the session 1906-7 contains the announcement that all intending students under sixteen years of age will, before admission to the evening classes, be required to pass an entrance examination in elementary mathematics and English, or to satisfy the principal that they possess the requisite preliminary knowledge. Those who do not possess the knowledge necessary to pass the entrance examination are recommended to join one of the evening schools which have been instituted in various parts of Salford, and at which the required preparation is provided. It is intended that next year all under seventeen years of age shall furnish evidence of the possession of the requisite preliminary knowledge. Is the early days of the movement for the higher education of women, one of its most active workers was Mrs. William Grey, whose death on September 19 at the advanced age of ninety years was announced in the Times of September 21. Mrs. Grey's name was from the first well known among those who advocated and carried to a successful result the foundation of high schools for girls by combined private effort; and the Girls' Public Day School Company (Ltd.) was the outcome of this movement. Springing out of the needs presently revealed by the high schools came the establishment of a system of training for secondary teachers. The idea was then comparatively new in England, and public opinion on the subject had to be formed and fostered, as it was largely through the work of Mrs. Grey. In recognition of her labours the well-known Maria Grey Training College for Women, now situated at Brondesbury, was named after her. Ax inspiring address on educational methods and their relation to science and industry, with particular reference to pottery, was delivered by Prof. H. E. Armstrong in the Town Hall, Longton, on September 19. In the course of his remarks, he said that workers in science have evolved a method, the scientific method, involving the gradual and cautious passage from the known to the unknown. Workers in politics have no such method at their disposal. Too often they are more or less ignorant of the real nature and extent of the problems which they deal with and seek to solve; sentiment masters their actions. The application of scientific method to public affairs is, consequently, becoming a matter of paramount importance. In all manufacturing districts science and industry must be brought into an effective alliance. On no other basis are prosperity and happiness possible, for the simple reason that, in these days, an industry that does not repose on a scientific basis is one which has no proper knowledge of itself, science being nothing more than organised systematic knowledge. Scientific training, training in method, is required by all. Scientific knowledge, true knowledge, must be public possession. The feeling is becoming general that something must be done to make our schools more effective than they are. In a recent report of the Consultative Committee, the Board of Education is advised that the schools have failed, in the past, to develop both the moral and mental qualities which are desirable, and that we must now strive to make the teaching far more practical, manual training being openly and strongly advocated. We read, moreover, It would seem clear to the committee that the thing needed is not only knowledge, but a right attitude of mind, a mind confident in its own power to observe and think, and in the habit of observing and thinking—a mind in which interest makes for intelligence and intelligence for interest. "The course, it is stated, "should consist of three threads or strands, roughly to be termed humanistic, scientific, and manual, and, in the case of girls, domestic; all higher elementary schools should give this threefold instruction." Though these views have been urged by many educational reformers for thirty years or more, the doctrine they involve is really quite revolutionary coming from such a quarter, especially as it is directed to the Board of Education, which treats manual training as a special subject for the select few. (d) The early appearance of an area of special differentiation in the vicinity of the primitive streak in the early blastoderm, and the later conversion of this "primitivestreak-area into an embryonic area " proper, by the primitive or annexation of the region surrounding the 66 "archenteric "knot. (e) The precise mode of disappearance of the ventral wall or floor of the archenteric- or invagination-cavity. (f) The occurrence of peculiar segmental cell-masses in the substance of the "primitive knot," where that constitutes the parietes of an archenteric canal or its representative. (g) The diagrammatically clear demonstration of various features of neural development, including the well-marked neuromeric segmentation of the cephalic region of the flattened medullary plate, the differentiation of early platelike ganglionic expansions of the neural crest in the cephalic region, the presence of various cellular connections between the cephalic ganglionic plates and certain of the neuromeric segments of the medullary plate. (h) The relative insignificance of the " archencephalic subdivision of the cephalic portion of the medullary plate, from which the fore-brain and most, if not all, of the midbrain are derived. or rays emitted by polonium, and which indicate that negatively charged secondary rays are produced when an aluminium or copper plate is bombarded by a stream of a rays. The method used may be briefly described as follows:A polonium-coated copper disc was placed in a glass tube with its active side facing, and parallel to, a highly insulated metal disc of the same size, which could be connected to one pair of quadrants of a sensitive Dolezalek electrometer. The distance between the discs could be adjusted. The polonium disc could be raised to any required potential by connecting it to a battery of small secondary cells. The glass tube was evacuated by means of a mercury pump down to a pressure of about 0.001 mm. and then sealed off, and the vacuum was then rendered as high as possible by the use of Dewar's method. The apparatus was placed between the poles of an electromagnet in such a manner that a magnetic field could be applied in a direction at right angles to the straight line joining the centres of the discs. The charge acquired in a given time by the insulated disc, when different strengths of magnetic field were applied, and when the electric field between the discs had different values, was measured. Tables of results are given, and these are also plotted in the form of curves, showing the variation of the current between the discs with varying magnetic and electric fields. From the results obtained the author arrives at the following conclusions : : (1) That under ordinary conditions, i.e. when not acted upon by an electric or magnetic field, the polonium gives off a larger amount of negative than of positive rays. (2) Under the influence of a gradually increasing electric field more and more of the slowly-moving negative rays are stopped, and the charge carried by the a rays becomes more and more predominant. (3) A potential difference of about 10 volts between the plates is sufficient to stop the last of the 8 rays. (4) The slowly-moving negative rays can also be prevented from striking the insulated plate by curling them up in a magnetic field. When they are stopped in this latter way, however, the quantity of positive electricity received by the insulated plate is only about one-fifth of that received when an electric field is used to stop the rays. The author explains this last fact as follows:When the potential difference between the two plates is 10 volts or more (the polonium being positive), the positive current from the polonium to the other plate consists of two parts, viz. a stream of positive a particles in the direction of the current, and a stream of negative particles in the opposite direction given off by the insulated plate. A magnetic field curls up this latter stream of negative rays, as well as the & rays given off by the polonium. The author also points out that his results showing the magnetic and electric deflection of the 8 rays are not in agreement with those obtained by Ewers with another sample of polonium. PARIS. Academy of Sciences, September 17.-M. Troost in the chair. The International Congress for the Study of the Polar Regions: G. Bigourdan. The congress was held at Brussels on September 7, and was attended by delegates representing fifteen countries and eighty learned societies. Seven standing committees were formed, each concerning itself with a special group of sciences. The formation of an International Polar Commission was decided upon, and bye-laws drawn up.-The deviations from the vertical in the region of the Sahel, Algeria: R. Bourgeois. In the triangulation of Algeria, the summit of the Voirol column was taken as the junction of the network of triangles. The national observatory, founded some years later, is about 5 kilometres in a direct line from this column. If the astronomical latitude of the observatory is compared with the geodesic latitude of the same point, the calculation being made starting with the fundamental coordinates of Voirol, a relatively considerable discrepancy is found, indicating a strong deviation from the vertical at one or other of these two points. In the present paper it is shown that it is the Voirol station which is at fault, and hence all the data built on this as a starting point require re-calculation.-The action of fluorine on chlorine, and on a new method of formation of hypochlorous acid: Paul Lebeau. Attempts were made to combine fluorine with chlorine, under varying conditions, at temperatures ranging from o° C. to -80° C. It was found that fluorine and chlorine do not combine directly. Liquid chlorine dissolves fluorine, but this fluorine is given off at the solidifying point of the chlorine. In presence of water, fluorine oxidises chlorine, the latter being completely converted into hypochlorous acid, thus giving a new method for the preparation of this acid.-Syntheses in the quinoline group phenylnaphthoquinoline dicarboxylic acid and its deri vatives: L. J. Simon and Ch. Mauguin.-The action of mixed organomagnesium compounds upon amides: Constantin Béis. To secure a reaction in all cases it is necessary to prepare the organomagnesium compound in the presence of the imide, the alkyl halide being added to a mixture of the imide, magnesium, and ether. Isoindolinones, isomeric with arylamidoketones, are obtained. -The hæmopoietic activity of the different organs in the course of the regeneration of the blood: Paul Carnot and Mlle. Cl. Deflandre. The experimental infection of trypanosomiasis by naturally infected Glossina palpalis: L. Cazalbou. Two out of seven specimens of Glossina palpalis, captured on the banks of the river Bani, a large tributary of the Niger, have infected dogs with trypanosomiasis. A cat was similarly infected.-The movement of the pole at the surface of the earth: Marcel Brillouin. A discussion of the curves published by M. Albrecht since 1890. The Standing 537 338 Meldrum: "Avogadro and Dalton. The Recent Radium Controversy.-Lord Kelvin, Stress in Magnetised Iron. Dr. C. Chree, F.R. S. 539 540 540 540 540 541 C. Some Scientific Centres.-IX. The Metallurgical Department of the Sheffield University. (Zilas• trated.) .... 541 541 543 544 Earth Eaters in India. By N. W. T. Geodetic Operations in South Africa. By W. E. P. 554 University and Educational Intelligence. 554 Societies and Academies. . . |