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most of the material was also analysed. The principal conclusions derived from their experiments by the authors are: (1) that in many sediments of all ages extremely fine particles, especially "quartz-dust," play an important part; (2) that most of the quartz-dust has been produced by the collision and abrasion of quartz grains while suspended in water, and that the perfect rounding of some quartz grains, usually assumed to be due to wind action, may be largely due to this subaqueous abrasion; (3) that carbonate of lime may often be present in suspension in considerable amount in natural waters; and (4) that the microscopic suspended matter is probably an important item in the total solid content of the waters of the open sea. In the same volume Messrs. T. Mellard Reade and Joseph Wright have a short paper on the Pleistocene clays and sands of the Isle of Man, which is mainly occupied by lists of the Foraminifera found in the drift.

ON May 15 the city of Nuremberg opened a national exhibition in commemoration of the centenary of its subjection to the Bavarian Crown. The exhibition, which will remain open until October, has proved eminently successful. It contains a good display of Bavarian manufactures, and is of special interest from the admirable manner in which the mineral resources of the kingdom are shown. The mineral deposits represented include the iron ores of the Fichtelgebirge, coal from the Palatinate, iron pyrites and galena from Bodenmais, salt from Berchtesgaden, copper ore from Imsbach, and graphite from

Passau.

THE Engineering Standards Committee has issued its standard specifications for material used in the construction of railway rolling stock. This report, No. 24 (London : Crosby Lockwood and Son, price 10s. 6d. net), covers sixtytwo folio pages, and is undoubtedly one of the most complete and valuable of the publications of the committee. It contains specifications for locomotive crank axles and straight axles, carriage and waggon axles, tires, springs, steel forgings, steel blooms, steel castings, copper plates, rods and tubes, brass tubes, and steel for plates, angles, and rivets. In each case specifications are given, with and without chemical analyses. The committee has also issued a standard specification for steel conduits for electrical wiring (report No. 31, price 2s. 6d. net), and a report (No. 28, price 2s. 6d. net) on British standard nuts, boltheads, and spanners.

In the Journal of the Franklin Institute (vol. clxii., No. 2) Mr. Clifford Richardson concludes his elaborate memoir on the petroleums of North America, in which he compares the character of those of the older and newer fields. Those of the earlier days of the industry, from the Appalachian field, were paraffin oils, free from sulphur, specially valuable for the production of illuminants. The petroleums of north-western Ohio and Canada, next developed, being sulphur oils, were far less valuable. The California oil is composed of such a series of hydrocarbons, of a non-paraffin nature, that its value is comparatively small. The oils from the more recently developed fields of Kansas and Texas are of variable character. Those from the Gulf Coastal Plain of Texas and Louisiana are so

variance. As one instance of how a locality may be influenced by some artificial feature the smoke of London is referred to, the effect of which is visible in the hilly villages of Oxfordshire when the wind is in the right quarter. Again, it is well known that in large cities the average annual temperature is higher than in the surrounding country, while the reduction of the amount of marsh land, e.g. in the Fen district, has probably had a decided effect upon the temperature. But these are local instances; whether the climate has changed generally is another matter. Hann and others have shown that there are evidences of changes of small amount sometimes in one direction and sometimes in another, e.g. the fluctuations in the size of European glaciers. The author assumes that British winters are later in coming than they used to be, and quotes that of 1894-5, "when the rigours of the season were scarcely felt until February, and were extended well into March.' A discussion of this frost in the Journal of the Royal Meteorological Society shows that the cold period commenced on December 30 and ended on March 5, with a break of a week's mild weather from January 14-21. On January 8 the temperature fell to -3° at Braemar, and was below 10° over the central part of north Scotland; after February 20 no readings below 10° were recorded. As to the influence of forests, we can have no better authority than Hann; they do reduce the mean air temperature, especially during the warmer part of the year, but whether they increase the amount of rainfall, and, if so, to what extent, cannot yet be definitely answered. We hope with Mr. Bastin that special attention will be given to this important subject in the future, and that, with better data at command, valuable conclusions may be obtained.

IN the American Journal of Science (vol. xxii., p. 176) Mr. S. E. Moody gives an account of experiments on the hydrolysis of iron, chromium, tin, cobalt, and nickel salts by solutions containing alkali iodide and iodate. In this reaction an equivalent quantity of iodine is set free, the estimation of which may be used for the quantitative determination of any of the above metals. In the case of zinc salts, the hydrolytic decomposition is only partial, and a basic salt is precipitated instead of the hydroxide.

IN the Annalen der Physik (vol. xx., p. 677) Dr. E. Marx gives an account of an experimental investigation relative to the velocity of Röntgen rays. It is estimated that the method and apparatus employed permit the velocity to be determined with an accuracy represented by a probable error of 1 per cent. Within this limit the velocity of propagation of Röntgen radiation is equal to that of light. This result furnishes strong evidence in favour of the view that Röntgen radiation consists in electromagnetic pulse transmission through the ether.

THE velocity of the a particle emitted by radium Cat various points of its path has been recently measured by Prof. Rutherford (Phil. Mag., xii., 134). After traversing 7.0 centimetres of air the a particle is no longer capable of exerting any sensible photographic action, although its velocity is still approximately four-tenths of the velocity with which it is emitted from the active source. The

strongly asphaltic as to be of value only for the produc- much more rapid decrease of the photographic effect of the tion of lubricants, for use as fuel, and as gas-oil.

"THE Effects of Civilisation upon Climate is the title of an interesting article by Mr. S. L. Bastin in the September number of the Monthly Review. As the author points out, the subject is by no means new, and is a matter upon which many authorities find themselves at

particle towards the end of its path as compared with the alteration in its kinetic energy necessitates the assumption of a certain critical velocity below which the particle is unable to produce the characteristic effects, or of a very rapid decrease in the velocity when this reaches a certain value.

IN the Zeitschrift für Elektrochemie (vol. xii., p. 513) Prof. W. Kistiakowsky points out the existence of a relationship between the surface-tension values of different liquids which is analogous to the well-known Trouton's rule. If k denote the capillary constant of a liquid at its boiling point, m the molecular weight, and T the boiling point on the absolute scale, then mk/T is constant and equal to 0.0116 for about forty non-associated liquids which have been examined. In the case of associated liquids, such as the alcohols and fatty acids, the value of mk/T is much smaller, and on account of the considerable change in the value of the factor it appears to be eminently suited for ascertaining the existence of association in the liquid state of aggregation.

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THE report of the principal chemist of the Government Laboratory for the year ending March 31 furnishes some interesting reading. The total number of samples examined at the laboratory at Clement's Inn Passage during the year was 106,779, the greater part being in connection with the revenue departments. In the Customs the increase in the number of samples examined, as compared with last year, was 2389, the Excise showing an increase of more than 18,000. Special attention was given to establishing a systematic check on the "obscuration of enumerated spirits, that is, the change in the apparent strength of spirits, as determined by the hydrometer, caused by the presence of solid matters in solution. It is noteworthy that, in the case of tea, the evidence of deliberate adulteration was extremely rare. A small proportion of the tea entering the country was declared to be unsound and unfit for human consumption. Such condemned tea does not pay duty, and, after being denatured by the addition of lime and asafœtida, is allowed to be used in the manufacture of caffeine. Little improvement is shown in the freedom from adulteration of the

beer supplied by publicans; 11.1 per cent. of the samples taken were found to be diluted. There is good reason, moreover, to believe that a notable amount of butter adulteration takes place in this country. A considerable increase is shown in the quantity of duty-free spirit used in colleges for purposes of research.

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SINCE the atomic weight of silver is the basis upon which most of the atomic weights of other elements are founded, even a small change in the accepted value is not without importance. The Comptes rendus for September 10 contains a note on this subject by P. A. Guye and G. TerGazarian. Owing to the great improvements in recent years in the methods of dealing with gases, physicochemical methods of determining atomic weights, originally only used as a rough guide for the purely chemical methods, have reached an accuracy at least equalling the latter. the atomic weights of carbon, hydrogen, nitrogen, and chlorine related directly to oxygen by physicochemical methods be taken as a basis, the value 107.89 is obtained for silver instead of 107.93, obtained by Stas by the use of chlorates, bromates, and iodates. The authors give a summary of the work done by various workers on the latter compounds, and note a possible cause of error in the presence of potassium chloride in the potassium chlorate used. They show that these two compounds, on account of the fact that the chloride forms a solid solution of nearly constant composition, are very difficult to separate. They find that potassium chlorate, purified as far as possible by re-crystallisation, contains 2.7 parts of chloride per 10,000. Applying this correction to Stas's figures, an atomic weight of 107.89 is obtained, nearly identical with

the figures of Marignac in the analysis of silver chlorate; of Dixon and Edgar, by the direct determination of the ratio H: Cl; and of Richards and Wells, the ratio Ag: AgCl. In this way the results of the chemical and physicochemical methods are brought into agreement, leading to the conclusion that the atomic weight of silver should be lowered from 107.93 to 107.89.

OUR ASTRONOMICAL COLUMN, ASTRONOMICAL OCCURRENCES IN OCTOBER:— Oct. 2. Pallas (mag. S'o) in opposition to the Sun. 9h. 19m. Minimum of Algol (B Persei).

3.

4.

6.

9.

15.

18-22.

23.

25.

,,

15h. 35m. to 16h. 52m. Moon occults μ Ceti (mag. 4'4).

12h. 30m. to 15h. 28m. Transit of Jupiter's Sat. III. (Ganymede).

16h. om. Jupiter in conjunction with Moon (Jupiter
2° 12' N.).

Venus. Illuminated portion of disc =0.333% of
Mars =0.976.

Epoch of October meteoric shower (Radiant 922 + 15 1.
11h. Im. Minimum of Algol (8 Persei).

6h. 49m. to 6h. 56m. Moon occults
(mag. 4:3).

19h. om. Venus at greatest brilliancy.

26. 7h. 50m. Minimum of Algol (8 Persei).

29.

Capricorni

Saturn. Major axis of outer ring = 42" 62; minor axis = 4" 73.

13h. om. Jupiter stationary.

THE TOTAL SOLAR ECLIPSE OF JANUARY, 1907.-In a letter to the Observatory (No. 374), Mr. W. T. Lynn discusses the accessibility and suitability of Andishan as a place wherefrom to observe the total eclipse of the sun which will take place in January next year. This town is situated to the north-east of Samarkand, in the Khanate of Khokand, its approximate position being long. = 72° 17' E., lat. -40° 50' N. It is on the Russian Central Asiatic Railway, about 170 miles south-east of Tashkent. Orenburg, the journey from Europe should prove a comAs a new line of railway runs to the latter place from paratively straightforward one. Andishan lies in the fertile valley of Ferghana, at the junction of the river Kara Darya (a tributary of the Syr Darya) and a smaller stream, so that there should be little difficulty in finding a suitable observing site for the eclipse parties. The eclipse will take place on January 14, 1907 (civil time), and the shadow track will be very narrow, thus limiting the choice of stations; the duration of totality will be about two minutes. By an obvious slip, the date is given as January 4 and the duration of totality as two seconds in Mr. Lynn's letter, as published in the Observatory.

OBSERVATIONS OF PHOEBE IN MAY AND JUNE, 1906 Circular 118 of the Harvard College Observatory gives the positions of Phoebe, the ninth satellite of Saturn, as determined from six photographs obtained between May 18 and June 28, with the 24-inch Bruce telescope, at Arequipa. The places thus obtained are compared with those given by the ephemeris published in the Nautical Almanac for 1906, the differences (O-C) in R.A. and declination being given.

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THE COLOURS OF SUN-SPOTS.-In the September number of the Bulletin de la Société astronomique de France M. Th. Hansen, of Praestö, Denmark, states that fomT many years' observations of sun-spots he is convinced that sun-spots exhibit colours proper to themselves, and not merely the results of instrumental chromatism. observes that the spot nuclei are rarely, if ever, a dead black, but generally are of a decided violet colour The preceding part of the spot is most often of a yellow colour, whilst red is generally predominant in the "following parts, although green is also seen there. On August *'. 1903, a small but dazzling white facula appeared in the centre of a black spot whilst M. Hansen was drawing the same. Two plates showing the colours observed in the large spot of November, 1903, accompany the commute

cation, and M. Hansen suggests that the colours of spots may eventually be differentiated by spectroscopic observations.

COLOURS AND MAGNITUDES OF DOUBLE STARS.—It is a generally accepted statement that when the magnitudes of the components of a binary-star system differ considerably their colours are also very different; similarly a slight difference in magnitude is usually accompanied by a similarity of colour.

Whilst preparing his recently published and valuable memoir on the double stars of Struve's "Mensuræ Micrometrica" Mr. Lewis has gathered striking evidence that these statements are true, and in No. 373 of the Observatory he gives a table of physical pairs, from which it is seen that a gradual increase in the differences of magnitude is accompanied by constantly increasing differences of colour. A discussion of fifty double stars situated in the southern hemisphere corroborates this evidence.

ROTATION PERIOD OF JUPITER'S EQUATORIAL REGION. In No. 4117 of the Astronomische Nachrichten Mr. Denning publishes the rotation periods, derived from a number of spots situated on the equatorial side of the southern equatorial belt of Jupiter, as determined by him at Bristol in the years 1898 to 1905-6 inclusive. From the tabulated statement given it is seen that the rate during 1905-6 was several seconds slower than in previous years. During 1880-3 the rotation period was from eighteen to twentyseven seconds shorter than during 1905-6.

GEOLOGY AT THE BRITISH ASSOCIATION, IT is only natural that the salient geological features of

the district in which the association meets should in some degree influence the character of the papers presented to Section C. Yorkshire, being rich in glacial and post-glacial problems, it is not surprising that special attention was directed to the more recent episodes in the earth's history. The presidential address dealt with British drifts and the inter-glacial problem, and, after a review of all the evidence bearing on the question, Mr. Lamplugh pronounces that no proof of mild inter-Glacial epochs, or even of one such epoch, has been discovered during the examination of glaciated districts in England, Ireland, and the Isle of Man. The "Middle Glacial " sands and gravels of our islands afford no proof of mild inter-glacial conditions or of submergence. In most cases, if not in all, they represent the fluvio-glacial material derived from ice sheets. Most of the fossiliferous beds regarded as inter-glacial contain a fauna and flora compatible with cold conditions of climate, and, in the exceptional cases where a warmer climate is indicated, the relation of the deposits to the Boulder-clays is open to question.

Prof. Kendall followed the president's address with a full and comprehensive account of the general geological structure of the country round York, and dwelt specially on the glaciation of the Vale of York and the Cleveland Hills. During the meeting the members were enabled to visit the York moraine and study the glacier lakes and overflows in the eastern part of the county under the guidance of Prof. Kendall.

Other local glacial papers dealt with the Kirmington Drift deposits, recent exposures of glacial drift at Doncaster and Tickhill, post-glacial deposits at Hornsea, and the plain of marine denudation beneath the drift of Holder

ness.

Contributions dealing with drift problems farther afield were presented by Mr. F. W. Harmer, who continued his work on the glacial deposits of the east of England, and in another paper he applied the brilliant results obtained by Prof. Kendall in the Cleveland district to support his theory regarding "Lake Oxford" and the origin of the Goring Gap.

The Rev. W. Lower Carter applied the same results to explain a dry valley which had been a glacier-lake overflow at Cwm-Coed-y-cerig, in South Wales, and gave a detailed account of the local glaciers which formerly existed in the valleys of the Usk and Wye.

Mr. R. D. Oldham brought forward a criterion of glacial erosion of lake basins, and Prof. J. W. Gregory

initiated a discussion on the problems connected with the Palæozoic glaciation of Australia, India, and South Africa. He pointed out that in Australia we have evidence of three horizons at which glacial beds occur, the Cambrian, the Carboniferous, and the Pleistocene. The Cambrian glacial beds near Adelaide range 400 miles north and south, and Cambrian fauna. Evidence of Pleistocene glaciers has only are interbedded with marine sediments containing a rich

The

been found on the mainland near the summit of Mt. Kosciusko, the highest mountain of Australia. Carboniferous glaciation is the most important, and presents points of the greatest interest. While in the State of Victoria there exists undoubted evidence of land ice

riding over an irregular land surface, in New South Wales, that were laid down below sea-level. West Australia, and in India the glacial beds include some Beds presumably of

this age are also found in South Africa, South America, and perhaps on the eastern flanks of the Urals. Prof. Gregory pointed out the inherent probability of these beds having formed part of a once continuous sheet of glacial deposits. No proof is forthcoming that they were synchronous, and in Africa and Australia the glacial evidence disappears to the north, ending about the southern tropic, and begins again in the northern hemisphere in latitude 17° 20' N., increasing in strength northwards to

Cashmere.

After a critical survey of the three theories which have been advanced to explain this problem, viz. (1) the shifting of the earth's axis (Oldham and Penck); (2) a universal refrigeration of the world due to a change in the composition of the earth's atmosphere (Arrhenius); and (3) local concentration of snowfall in consequence of a different distribution of land and water, Prof. Gregory concludes that the last is alone adequate to explain the facts.

In the discussion which followed, Prof. Edgeworth David and Mr. T. H. Holland argued in favour of Arrhenius's theory, as the cause must have been worldwide, and the phenomena could not be accounted for by local changes in topography. Mr. R. D. Oldham favoured Prof. Chamberlain's adaptation of Arrhenius's carbonic acid theory, and pointed out the analogies between the great revolutionary epochs of the earth's history, all of which are associated with glacial phenomena.

The stratigraphical papers certainly showed a bias towards the Carboniferous period. No less than five papers were read, dealing mainly with the faunal succession and zoning of beds of this age. The recent work of Dr. Wheelton Hind, Dr. Vaughan, Prof. Garwood and others, as detailed in their papers, shows great strides towards the completion of what, at one time, seemed a hopeless problem.

A discussion on the origin of the Trias was opened by Prof. Bonney and Mr. J. Lomas. Prof. Bonney considers the Bunter to be chiefly of fluviatile origin, the rivers carrying the materials having their origins in Scotland, the extreme north of Ireland, and another flowing from the south-west. The Keuper he regards as indicating the setting in of inland-sea conditions, and the Red Marl as having been deposited in a great salt lake. The physical and climatal conditions of the Trias were probably to some extent comparable with those now existing in certain of the more central parts of Asia, such as Persia or Turkestan.

Mr. Lomas compared the Triassic deposits with those now forming in desert regions. He pointed out that the dominant feature of deserts is concentration. The wind acting on loose material concentrates particles of equal size in one place, an arid climate tends to concentrate the salts brought down by rivers in solution in shallow pools held up by the irregular disposition of sand dunes, and animal and plant life is concentrated in those regions where water is more or less permanent. Taking the various divisions of the Trias, he showed that in the Bunter the pebble beds of the Midlands may be compared with those of Lancashire and Cheshire, the only difference being that the former may have been subject to the sifting action of wind, which has removed the smaller sand particles, while the latter has, in part, escaped this action, and has been augmented by material from the south. The Upper Bunter he cited as a striking example of concentration of particles of even size. The Keuper shows evidence of similar sift

ing, and is characterised by an increasing frequency of Marl bands. These he regards as evidences of shallow lakes, and compares them with similar pools now found in the desert regions of South Africa. The muds forming the floors of these pools, both in the recent and older examples, contain Estheria, and afford impressions of footprints, raindrops, and desiccation cracks. The Keuper Marls he compares with the Loess of eastern Europe, and the beds of salt, gypsum, and other salts he regards as the result of evaporation in lakes.

Mr. Holland referred to certain phenomena in the Rajputana desert that supported Mr. Lomas's views with regard to the processes of concentration in arid regions, and gave evidence of the sifting action of wind in India. Similar bands of silt and mud are found filling in hollows in the Archæan rocks. He was not prepared to admit that the features of the British Trias were due only to wind action, but in the main they were due to conditions prevailing in desert regions. Prof. Cole pointed out that, in dealing with the British Trias, we must not forget the great sea eastwards and the likelihood of the establishment of a monsoon system on its margin. This might set up an intense rainy season for, say, three months in the year, followed by a dry season. Sheets of pebbles without well-defined water channels are compatible with general evidence of desiccation. Mr. R. D. Oldham showed that the only agency forming pure sands comparable with the Trias is wind. Mr. Clement Reid compared the peculiar stiff-stemmed flora of the desert with those found in the Trias.

The papers dealing with palæontology were more than usually interesting. Mr. C. G. Danford exhibited and described a fine series of ammonites from Speeton. Mr. A. C. Seward dealt with the Jurassic flora of Yorkshire, and Dr. H. Woodward, in describing a wonderful collection of arthropods from the Coal-measures at Sparth Bottoms, showed what an enthusiastic band of collectors can do, when work is taken in hand in the spirit which characterises the Rochdale geologists.

The report on the fauna and flora of the Trias included an important paper by Dr. A. Smith Woodward on Rhynchosaurus articeps, and Mr. H. C. Beasley and Mr. Lomas described the great finds of Triassic foot-prints which have recently been discovered at Storeton, in Cheshire, and Hollington, in Staffordshire.

In petrology and mineralogy great interest was shown in the announcement by Prof. Edgeworth David that diamonds had been found embedded in the matrix near Inverell, New South Wales.

Mr. T. H. Holland demonstrated the peculiar properties of a variety of sodalite from Rajputana. When freshly broken it has a bright carmine colour, which changes to dull grey on being exposed to light. The carmine colour returns when the specimen is kept in the dark. Prof. H. S. Reynolds dealt with the igneous rocks in the district south-west of Dolgelly, and described the occurrence of a picrite from the eastern Mendips.

In general geology Mr. J. Parkinson gave an interesting account of the post-Cretaceous geology of Southern Nigeria, Prof. Cole outlined a scheme of geology suited to agricultural scholars, and Prof. J. Milne discussed certain earthquake relationships.

While the time of the section was fully taken up by the consideration of the above subjects, no less than thirtyseven papers dealing with strictly geological matters were read in other sections. J. L.

ZOOLOGY AT THE BRITISH ASSOCIATION. THE large attendance at many of the meetings of Section D was sufficient evidence of the general interest of the programme, which included discussions upon the Tanganyika problem, the nature of fertilisation, spicule formation in sponges, the bearing of scientific marine investigations on practical fishery problems, and a number of papers on special subjects, only a few of which can be noticed here.

The Tanganyika Problem.

The discussion on the Tanganyika problem was opened by Mr. J. E. S. Moore, who dealt, first, with the characters of fresh-water faunas in general, pointing out

the wide distribution of many fresh-water organisms over the land surfaces of the world. He held that the difficul ties in the way of the migration of these animals were so great that their wide distribution could not be attributed solely to such migration. He suggested that in all prob ability the sea is becoming more salt, and that this change may have been concerned in the production and separation of marine and fresh-water faunas. Whatever the actual cause of separation, as the general fresh-water fauna of the globe possessed certain archaic characters it would be convenient to name this the primary fresh-water fauna To this primary fauna there are added in many places, e.g. in the Caspian Sea, animals which have, from their structure and affinities, been obviously derived from the sea, and have an origin independent of that of the fresh-water fauna of the region in which they occur. To these animals Mr. Moore applied the name halolimnic. There are in Tanganyika a number of animals peculiar to that lake, and regarded by Mr. Moore as halolimnic. The mollusca of the lake are represented by certain ordinary fresh-water forms. but, in addition, there are several not closely related to any recognised fresh-water type, nor does their anatomy suggest that they have been evolved from any African fresh-water form; there are four Polyzoa, only one of which is phylactolæmatous, and it may be inferred that the other three are derived from marine forms, while the occurrence of a medusa is also suggestive in this connection. There are three possible explanations of these faunistic peculiar ties (1) that they are due to direct modifications of the general African fresh-water fauna; (2) that they are constituted by the presence in the lake of the remains of an extinct fresh-water fauna; (3) that they are due to the presence of halolimnic elements. Mr. Moore regarded the last as the correct explanation, and referred to the similarity of the shells of certain Tanganyika gastropods to those common in Jurassic seas. The evidence points to Tanganyika having been isolated a long time from the

sea.

Mr. W. A. Cunnington gave a brief account of the third Tanganyika expedition, from which he had recently returned. 115 fishes are now recorded from the lake, 102 of which occur nowhere else. Twelve species of prawns (oi which only one has been found elsewhere) are all specialised in the direction of reduction of gills, and the four species of crabs are all endemic. These facts are probably to be explained by the long isolation of the lake. It is curious that no Cladocera were met with in Tanganyika, though they are abundant in Victoria Nyanza and Lake Nyassa.

Prof. J. W. Gregory considered that there are no evidences of marine rocks in the plateau of equatorial Africa, though it is evident that the plateau is of great antiquity. The idea of the occurrence of the sea in the Tanganyika valley should be abandoned. He suggested that the "halolimnic" fauna is rather to be explained as a part of an ancient lake fauna at one time widely distributed over Africa, but now surviving only in Tanganyika. Prof. Pelseneer pointed out that the external resemblances of shells are often illusory, and the results to which they lead quite uncertain, therefore only the study and comparison of the internal organisation of the molluscs can throw light on the question at issue. Messrs. Moore and Digby have suggested that some of the Tanganyika molluscs have affinities to certain marine forms, Chytra being related to Hipponyx and Capulus, Spekia to Lamellaria, and Edgaria (= Nassopsis) to the Architanioglossa; but Prof. Pelseneer held that there are really no affinities, in the usual sense of the word, between these forms, but only distant resemblances, such as are common to all the Tænioglossa, to which group these "halolimnic" forms belong. Nor do they present archaic characters to a greater extent than other fresh-water genera halolimnic," such as Ampullaria and Paludina. Prod Pelseneer concluded that all the "halolimnic" gastropods belong to the family Melaniidæ or to closely related types. as is shown by their radulæ, otocysts, &c., and by special details of their biology-their fresh-water habitat and viviparity. The study of two genera (Giraudia and Lavigeria) the organisation of which has only just heer investigated supports this conclusion. Both have in their otocysts multiple otoliths, one otolith being much larger

not

than the others in two species of Giraudia. Lavigeria, the only genus of which a female has been examined, is viviparous, and its radula most closely resembles that of the Melaniid genus Chiara, while the radula of Giraudia is clearly similar to that of the Melaniid genus Ancylotus.

Dr. G. A. Boulenger, in reviewing the evidence afforded by a study of the fishes, said that the Cichlid fishes, which form so large a proportion of the fishes of Tanganyika, are examples of an extraordinary modification of one type which has entered fresh water all over Africa, and that this lake seems to have served as a nursery for genera and species of this family. The Cichlids of Victoria Nyanza seem to have arisen, like those of Tanganyika, from a small number of generalised types. The fishes of Tanganyika indicate a long isolation of the lake, perhaps extending back to Miocene times.

The Nature of Fertilisation.

The discussion (conjointly with Section K) on the nature of fertilisation was initiated by Dr. V. H. Blackman, who gave a brief account of the recent work on which the present views of fertilisation are based, dealing specially with the role of the chromosomes, and taking as a starting point the theory put forward by Montgomery (1901), that in synapsis the maternal and paternal chromosomes unite in pairs and are later separated by the reduction division, which thus divides the somatic chromosomes into two groups. Fertilisation appears to be incapable of exact definition, for apogamy and parthenogenesis link it on to vegetative reproduction, and, indeed, nuclear fusions and reductions occur in plants apart from reproduction, e.g. in graft hybrids of Mespilus and Crataegus there is evidence that the fusing of vegetative cells has led to the mixing

of characters.

Prof. Calkins described his experiments proving that it was possible to carry cultures of Paramecium through a certain number of periods of depression, and to renew their vitality by means other than nuclear fusion (conjugation), he having been able to do this by treatment with beef extract and with extract of pancreas and brain. Prof. M. Hartog cited what he considered to be comparable cases of the orange, Funkia, &c., where cells of the nucellar tissue grow into the embryo-sac cavity, and, under the stimulus of the exceptional nutrition, grow into embryos which behave exactly like the normal embryos produced by the fertilised oosphere in the same favoured feeding place.

Mr. L. Doncaster gave a brief account of the maturation of parthenogenetic eggs, pointing out that many eggs which produce, not only one, but two polar bodies, may develop parthenogenetically. The fate of the polar nuclei varies considerably; in some cases they are cast out and lost, in others they remain in the egg, and (as in Artemia) one may conjugate with the egg nucleus, taking the place of the spermatozoon.

Dr. Rosenberg (Stockholm) described his experiments on the production of hybrids of Drosera rotundifolia and D. longifolia, the cells of the former having ten and of the latter twenty chromosomes. In certain of the daughter nuclei, ten, eleven, or twelve chromosomes move to one pole during division, the same number to the other pole, and between these lie a number of separate chromosomes, which are later taken into one or other of the division nuclei. In Hieracium, one polar nucleus returns to the embryo-sac cell and fuses with the egg-cell, producing a cell with unreduced number of chromosomes. Dr. Ostenfeld afterwards stated that Hieracium was able to produce fruits without ordinary fertilisation having taken place. Prof. Hickson considered that the evidence that the chromosomes are the sole bearers of the hereditary characters had been much weakened during recent years by the results of such experiments as those on enucleated eggs fertilised by the sperms of another species, which gave rise to larvæ showing sometimes paternal and sometimes maternal and mixed characters.

Mr. H. Wager pointed out that in many of the lower organisms the nucleus does not seem to be concerned, as in higher organisms, in the blending, during fertilisation, of two distinct lines of descent, but presides over the nutritional activities of the cell, and fertilisation is replaced by various nutritional devices.

Spicule Formation in Sponges.

Prof. Minchin discussed a number of facts bearing on spicule formation in calcareous sponges, and concluded that the form of primary spicules is in no way dependent upon the physical properties of the material (calcite), but is regulated solely by biological conditions. When, however, primary spicules are joined together to form spicular systems, the physical properties of the material may exert an influence upon the form of the spicule as a whole by determining the angles at which the rays join together. Prof. Dendy dealt more particularly with the evolution of the various forms of siliceous spicules in the Tetraxonid sponges, showing that they are all derivable from a primitive tetraxon form. He showed that these spicules originated singly in mother-cells, and endeavoured to explain their great diversity of form as the result of the action of variation, heredity, and natural selection. Mr. W. Woodland contended that the forms of spicules are not inherited, for such an inheritance of forms of spicules adapted to the architecture of the organism implies that wandering cells (scleroblasts) are severally able to produce a part of the adult organism, an organ, in fact, related in form to the other parts. The collection of scleroblasts disposed about the spicule forming the protoplasmic mould in which the spicule is deposited is the organ assumed to be inherited. Such a theory seems to be contradicted by the facts of experimental embryology, which shows that a blastomere can only give rise to an integral part of the adult organism in virtue of its localised connection with other blastomeres. Mr. Woodland concluded, therefore, that the form of the deposited spicule determines the disposition of the scleroblasts, and not vice versa (as held by the advocates of the inheritance of spicule form), and that spicular phenomena may be fully explained by reference to known physical facts. He suggested that many spicules are probably closely allied in their mode of origin to the curious structures (colloidomorphs) formed by mineral substances deposited in colloidal media.

Fishery Problems and Marine Investigations.

Dr. E. J. Allen opened a discussion on the relations of scientific marine investigations to practical fishery problems. He pointed out that the great growth of the fishing industry during the last thirty years has been accomplished by practical fishermen, and, in some directions at least, science could even now help little, e.g. in the case of driftnet fisheries any attempt to increase the supply would probably be futile. In the case of trawl fisheries a diminution in the source of supply has taken place, but there is hope of increasing the actual supply of fish in the grounds by (1) regulation and restriction of fishing; (2) re-stocking exhausted grounds by hatching or by transplantation; and (3) destruction of the enemies of food fishes. Before such measures can be carried out with much hope of success, a complete and exact knowledge is necessary of the habits and life-histories of the fishes, and of the conditions under which they live.

This

Dr. W. Garstang discussed the question of the diminution of the stock of plaice in the North Sea, and the methods suggested for increasing the supply. The diminution is supposed to be caused by the excessive fishing of young fish. In the southern part of the North Sea (Flemish Bight) most of the fish caught are less than 30 cm. in length, while on the Dogger Bank most are more than 30 cm. long. From January to June the small plaice are found chiefly inshore and out to the 11-fathom line; from June to December they travel out to the 20-fathom line. gives a rough idea of the migration of the young plaice outward into deeper water during the summer and autumn months, and is confirmed by the results of marking experiments. The migration of fish to the Dogger Bank is, therefore, not a direct and simple one, but takes place in at least two stages. Much more information is still required concerning the normal distribution of fishes of various sizes, the migration of young fish, and the causes which determine rapidity of growth.

Mr. G. L. Alward expressed his belief in the value of fish hatcheries, and also advocated the exploration of the area between Norway and Iceland in the hope that new fishing ground may be found so as to relieve the present

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