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advanced by the authorities quoted by Mr. Bateson which in be regarded as antagonistic to this impression by any one ho knows a little about the working of heredity in insect

irieties.

A word about "showcases." I hope that no reader of ATURE may be led to think lightly of these as a means of struction, and as one of the chief objects of a great museum, cause Mr. Bateson states that there is a wrong identification in e at the Royal College of Surgeons, and because of the distincon which he is so careful to draw between these and other ses. Some of the most valuable specimens in the world are in showcases." They form one of the most admirable features modern museum arrangement, and the best material obtainable set aside for them. This is equally true on the continent and our own country, where Prof. Sir W. Flower and Prof. ewart have devoted an immense amount of time and labour this department, an important recent feature of both their useums being the illustration of the uses of colouring in imals. Prof. Lankester too is developing the same method instruction with great success in the Oxford Museum.

It is in no way remarkable or reprehensible that four recent iters (Mr. Lloyd Morgan, Mr. Beddard, Mr. Romanes, and yself) concerned with this subject and knowing the care taken choosing these illustrations, should also make use of some of em in their published works.

One difficulty" brought forward by Mr. Bateson is so tile that I did not allude to it before, and only refer to it now cause he repeats it. He seems to think that doubt is thrown the theory of mimicry because V. pellucens does not resemble wasp, and yet lives in its nests as if any believer in natural ection maintained that all closely allied forms must defend emselves in the same way!

As to Mr. Bateson's statement at the end of his letter that he ly intended to draw attention to the matter (and not to hurt thereby), I can only say that this statement implies an raordinary want of acquaintance with the niceties of the glish language. It is so easy to correct mistakes without ving anything but a feeling of gratitude in the mind of one o has made them, that, in justice to Mr. Bateson's intelliI am compelled to doubt the accuracy of his memory. Oxford, November 27. EDWARD B. POULTON.

ice,

"A Criticism on Darwin." [ WRITE to protest against what appears to be a growing it on the part of certain publishing hrms of advertising their ks in a must misleading manner, viz. by selecting any ase from a notice of the book which may serve to indicate t the writer's opinion on the work as a whole is favourable, ereas, if quoted with its immediate context, the passage would ve the precise opposite. For example, I see in NATURE and where an advertisement of Mr. David Syme's book "On Modification of Organisms; a Criticism of Darwin" (Simp , Marshall, and Co.), in which I am quoted as having called writer "a shrewd critic." Standing by itself these words ly that I have somewhere recommended the work as well thy of perusal. The fact of the matter, however, is, that the ds occur in a foot note which I added to the proof of my rely published book on “Darwin and After Darwin," for the essed purpose of showing the extraordinary confusion of I which still prevails on the part of Darwin's critics, even with ence to the very fundamental parts of his theory.' Elsee in the same foot-note I refer to the writer's "almost rous misunderstandings"; and conclude by saying that he ows himself a shrewd critic in some other parts of his essay, e he is not engaged especially on the theory of natural tion.' I may now add that the only parts of his essay hich these advertised words apply are those where he s of the deleterious effects of in-breeding.

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GEORGE J. ROMANES.

Animals' Rights.

AM not surprised that you should find my essay on imals' Rights" an "absolutely useless " one, for I nly did not design it to be a congenial hand-book for the gists of Vivisection. Nor do I the least object to your ng what conclusions you like from the premisses laid by me, even though you seek your justification of tion from the very definition that seems to me to be But, as a matter of fact, clearly condemnatory of it.

and not of personal opinion, I beg to point out that you have utterly misrepresented the leading principle of the book, and that the two contradictory definitions of animals' rights, which you attribute to my confusion of mind, are in reality the phantom creation of your own. On p. 9, in referring to Herbert Spencer's definition of human rights, I claim for animals a "due measure" (not an equal amount) of the same "restricted freedom"-a claim which by no means prohibits all use and employment of animals, as you conveniently assume. On p. 28 I give, not a second definition, but a repetition and amplification of the one given on p. 9; and the "due measure of restricted freedom" is explained as being "a life which permits of the individual development, subject to the limitations imposed by the permanent needs and interests of the community." Surely this is intelligible enough; yet the reviewer has utterly failed to understand it. H. S. SALT. 38 Gloucester Road, N. W., November 26.

Induction and Deduction.

MISS JONES has not quite understood me. I maintain that definitions should be arbitrary, but not necessarily that they should be made at random. If they are so made it will, as she points out, seldom happen that they turn out useful, or have any real applications, though this would not affect their logical validity if it amused any one to make them and investigate their consequences. Such definitions with no real applications are actually made by pure mathematicians. The peculiar value of the definitions of geometry consists however in the fact that they have so many real applications, and it is only by a long process of survival of the fittest that a few such happy definitions are weeded out from among the many which lead to nought. The definitions of geometry could not now be laid down at random, but they are none the less arbitrary, for they require no support from any à priori considerations. EDWARD T. DIXON. Trinity College, Cambridge, November 28.

The Present Comets.

I HAVE to notice the following mistake in my letter which appeared in NATURE (vol. xlvi. p. 561). I called comet Brooks, comet "c." I now find it should be called comet "d."

I have since writing been quite satisfied that the head of comet Swift extends less towards the n than towards the s (as T. W. BACKHOUSE. suggested in my letter). West Hendon House, Sunderland, November 26.

The Afterglow.

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AFTER witnessing, with Profs. Lyon and Orr, remarkable effects of afterglow on November 27, I waited for the next issue of NATURE (No. 1205), in the expectation that similar phenomena would be mentioned as having been seen in the British Isles. Curiously enough, the letter on Afterglow" in that issue comes from Honolulu, dated November 8. It is possible, however, that the effects of volcanic dust from one of the great eruptions of the past summer are now beginning to be noticeable in opposite hemispheres. The Krakatão eruption of August 27, 1883, appears to have caused exceptional afterglows in Honolulu on September 5, and in Western Europe by November 9, in the same year.

From the top of Killiney Hill, on November 27, at 4 30 p m., we witnessed an extraordinary combination of cloud-effects, such as I do not remember having seen since the winter of 1883-4. On the west, dense clouds were forming upon Two Rock Mountain, and streaming down into the hollow of Carrickmines; but beyond them a clear golden sunset, passing above into green and intense blue, was visible above the summits of the hills. Fleecy cirrus clouds in the zenith were a delicate pink against clear blue, and this glow extended to all the higher cloudmasses in the east, unul the sea itself became rose-pink by reflection. But in the extreme east the exceptional magenta tints, almost violet, that characterized many of the Krakatão glows, were strikingly apparent, though in part veiled by the low grey cloud of the Channel. These effects were at their maximum when the sun had set half an hour; they would doubtless have been of much longer duration but for the near clouds forming on the mountains.

One's thoughts at once turned to the great eruption of Sangir in the Philippines, which occurred, however, as far back as

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(5) That a material standard, constructed in s metal, should be adopted as the standard ohm, 1 should from time to time be verified by comparison a column of mercury of known dimensions.

(6) That for the purpose of replacing the standır. lost, destroyed, or damaged, and for ordinary se limited number of copies should be constructed = should be periodically compared with the standard

(7) That resistances constructed in solid metal s be adopted as Board of Trade standards for mit and submultiples of the ohm.

(8) That the value of the standard of resistance.

To the Right Hon. A. J. Mundella, M.P., President of structed by a Committee of the British Associa

the Board of Trade.

Subsequently to the presentation of our former report to Sir Michael Hicks-Beach in July, 1891, we were informed that it was probable that the German Government would shortly take steps to establish legal standards for use in connection with electrical supply, and that, with a view to secure complete agreement between the proposed standards in Germany and England, the Director of the Physico-Technical Imperial Institute at Berlin, Prof. von Helmholtz, with certain of his assistants, proposed to visit England for the purpose of making exact comparisons between the units in use in the two countries, and of attending the meeting of the British Association which was to take place in August in Edinburgh.

Having regard to the importance of this communication, it appeared desirable that the Board of Trade should postpone the action recommended in our previous report until after Prof. Helmholtz's visit.

That visit took place early in August, and there was a very full discussion of the whole subject at the meeting of the British Association in Edinburgh, at which several of our number were present. The meeting was also attended by Dr. Guillaume, of the Bureau International des Poids et Mesures, and Prof. Carhart, of the University of Michigan, U.S.A., who were well qualified by their scientific attainments to represent the opinion of their respective countries.

It appeared from the discussion that a few comparatively slight modifications of the resolutions included in our previous report would tend to secure international

agreement.

An extract from the report of the Electrical Standards Committee of the British Association, embodying the results of this discussion, was communicated to us by the Secretary, and will be found in the appendix to this report. Having carefully reconsidered the whole question in view of this communication, and having received the report of the sub-committee mentioned in resolution 14 of our previous report, we now desire, for the resolutions contained in that report, to substitute the following:

RESOLUTIONS.

(1) That it is desirable that new denominations of standards for the measurement of electricity should be made and approved by Her Majesty in Council as Board of Trade standards.

(2) That the magnitudes of these standards should be determined on the electro-magnetic system of measurement with reference to the centimentre as unit of length, the gramme as unit of mass, and the second as unit of time, and that by the terms centimetre and gramme are meant the standards of those denominations deposited with the Board of Trade.

(3) That the standard of electrical resistance should be denominated the ohm, and should have the value 1,000,000,000 in terms of the centimetre and second.

(4) That the resistance offered to an unvarying electric current by a column of mercury at the temperature of melting ice 14:4521 grammes in mass of a constant cross sectional area, and of a length of 106'3 centimetres may be adopted as one ohm.

the Advancement of Science in the years 1863 and and known as the British Association unit, may be t as 9866 of the ohm.

(9) That the standard of electrical current shop. denominated the ampere, and should have the vali? tenth (o) in terms of the centimetre, gramme. second.

(10) That an unvarying current which, when p through a solution of nitrate of silver in water, in an ance with the specification attached to this report, dej silver at the rate of 0'001118 of a gramme per e may be taken as a current of one ampere.

(11) That an alternating current of one ampere mean a current such that the square root of the average of the square of its strength at each ins amperes is unity,

(12) That instruments constructed on the print the balance, in which, by the proper disposition conductors, forces of attraction and repulsion are duced, which depend upon the amount of current ph and are balanced by known weights, should be. as the Board of Trade standards for the measurem

current whether unvarying or alternating.

(13) That the standard of electrical pressure be denominated the volt, being the pressure w ohm, will produce a current of one ampere. steadily applied to a conductor whose resistance

(14) That the electrical pressure at a tempora 15 centigrade between the poles or electrodes voltaic cell known as Clark's cell, prepared in acc with the specification attached to this report, taken as not differing from a pressure of 14340" more than one part in 1000.

(15) That an alternating pressure of one v mean a pressure such that the square root of the average of the square of its value at each instant is unity.

(16) That instruments constructed on the pr and, for high-pressures, instrument on the pr Lord Kelvin's quadrant electrometer used idios the balance, electrostatic forces being balance a known weight, should be adopted as Board standards for the measurement of pressure, whe varying or alternating.

COURTENAY BOYLE.
KELVIN.

P. CARDEW.
W. H. PREECE.
RAYLEIGH.

November 29.

THE

G. CAREY FST R. T. GLAZER J. HOPKINSON W. E. AYRTOY

T. W. P. BLOMEFIELD, Secretd

ON THE PHYSIOLOGY OF GRAFT 'HE volume before us contains the record years of research upon the effects of differe of grafts (using the term in its widest significare vegetable kingdom.

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Opening with an historical introduction which deals Liefly with the development of the art from classical nes down to the present day, the author proceeds to dicate the general scope of his own investigations, and describe the methods of experiment which he employed. he immediate problems which he sets himself to solve e contained in two questions which occur on an early ge of his book, namely—Is it possible to remove parts a given plant and transplant them to any other position the same or a similar plant? And upon this question lows the second -What is the nature of the reaction ich occurs between the newly-introduced portion and surrounding tissues?

But although these form the proximate questions which to be answered by means of a large number of wellnducted experiments, it soon becomes clear to the der that the chief interest which attaches to the results tained depends on their application to the theory of larity of cells and tissues which Prof. Vöchting has alidy put forward elsewhere.

The plants chiefly (but by no means exclusively) used in investigations were Beta vulgaris and Cydonia japo

ne.

The former is of a fleshy and succulent character, ilst the latter is a woody plant which happens to be ecially adapted to the various operations of grafting, d, as it is a perennial, it admits of the results of the periments being watched for a considerable period of Prof. Vöchting distinguishes in every part of the nt between a "shoot-pole" and a "root-pole," and :se he considers to be always present, however small plant member, or piece of excised tissue, may be. e polarity manifests itself at the free surfaces, much as effects of the magnetism of a bar magnet are visible ts ends; and moreover, just as the pieces of a broken gnet are themselves duly polarized, so also fragments tissue exhibit relations of polarity identical with those iracteristic of the organism from which they were ived The first precaution necessary to secure success in fting is to respect the existences of the shoot- and rootes, and to insert the scion in such a way as to bring poles into due correspondence with those of the stock. ting upon this principle it is found that, generally aking, any member may be grafted on any other mber unless there is some special reason to the conry, such as may be connected, for example, with nuion or water-supply. The leaf of the beet will "take" rafted on a root, and vice versa, and it was also found t it was possible, in the case of roots with diarch idles, to effect a union even when the xylem planes he two portions were made to cross each other at it angles; analogous results were also obtained with es. Hence the author concludes that there is no erent fixity in the organization of plants which prermines a definite sequence of the chief members of h they are composed.

xperiments were made with the object of determining nutual reactions between the stock and the scion, and conclusion arrived at is that beyond such changes as be referred to nutritional and similar causes, the remain unaltered, at least in so far as their specific acters are concerned. Prof. Vöchting criticises unrably the various alleged cases of the so-called ft-hybrids," and points out that even in one of the authenticated examples, that of Cytisus Adami, all pts to produce the hybrid afresh have resulted in

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difficulties arise in the accomplishment of a complete union, and these difficulties are further increased to a maximum when the tissue is put in upside-down, so to speak, that is with its own poles presented to similar poles in the stock. A great number of experiments were instituted to investigate these reactions, but space forbids any attempt to do more than briefly summarize the most important points. In the case of Cydonia japonica a ring of rind was cut out of a twig and replaced in the reversed direction. In many cases the twigs behaved as if the tissue had not been restored at all, simply dying, whilst in others a subsequent healing took place. This healing was accompanied by a swelling at the upper junction, together with the appearance of a ridge of tissue which was formed along the longitudinal suture of the ring from above downwards and was derived from the cambium of the ring, and not by an ingrowth of callus from the uninjured cortex of the twig, as might perhaps be supposed. In this way connection between the interrupted rind was re-established, and growth recommenced. But both at the edges of the tissue-ridge, and also between it and the original underlying xylem, the cell elements were found to be disposed in a remarkable manner, forming curved unions with the cells of the healthy tissues. For the histological details the reader is referred to the original treatise; suffice it to say that Prof. Vöchting believes that he has found in the appearances thus presented, additional evidence for the validity of his theory of the polarized condition of living tissues. He conceives of these polarities as properties which are the expression of the innermost relationships existing between the con. stituents of which cells are built up. He further regards the polarity of any tissue as irreversible when once the direction has been imparted to it, and he finds justification for this view not only in the details of his own experiments on grafting, but also in the results of investigations conducted by Kny and others, on the effects of compelling parts of plants to grow in a reversed position. After discussing some of the objections to his theory, without, however, disposing of them all, the author concludes by stating, with considerable reserve, some of the wider applications of his theory in explaining geotropism and other allied phenomena.

The book certainly forms one of the most important of the recent contributions to plant physiology, and the experimental details are well illustrated in the eleven plates which accompany the text, whilst the diagrams in the body of the work serve to render the author's theoretical views more intelligible. J. B. F.

NOTES.

A GOLD MEDAL is to be presented to M. Pasteur on December 27, his seventieth birthday.

ON Monday Lord Durham laid the foundation stone of a new wing of the College of Science, Newcastle, which, like the College of Medicine in the same city, is a branch of the Durham University. The College of Science was established at Westdation stone of the present premises at Barras Bridge in 1887, gate-hill, Newcastle, in 1871. Lord Armstrong laid the founand in the following year the existing wing was opened by the Marquis and Marchioness of Lorne. The success of the institution is strikingly indicated by the fact that the increase in the number of students has rendered a new wing absolutely neces

sary.

DR. WERNER SIEMENS, the well-known electrical engineer, died at Berlin on Tuesday. He was seventy-six years of age.

MR. W. H. PREECE, F. R. S., has been appointed a member of the Royal Commission on Electrical Communication with Lighthouses, &c., in the place of Mr. Edward Graves, deceased.

MR. W. MATTIEU WILLIAMS, who had a considerable reputation as a metallurgist and a popular writer on scientific subjects, died at his residence, near Willesden, on November 28. He was in his seventy-fourth year. Among his writings are his well-known books on "The Fuel of the Sun," "Science in Short Chapters," and "Through Norway with a Knapsack."

WE have to record the death of two distinguished Continental cryptogamists, Dr. F. v. Thumen, the well-known mycologist, formerly Director of the Chemico-Physiological Experiment Station at Klosternenberg; and Dr. C. M. Gottsche, of Altona, one of the authors of the Synopsis Hepaticarum, and one of the leading authorities on Mosses and Hepaticæ, in the eighty-fourth year of his age.

The Master and Fellows of Gonville and Caius College, Cambridge, have elected as Honorary Fellows the following graduates of the college :-Alexander Henry Green, F. R.S., bracketed sixth Wrangler, 1855, formerly a Fellow of the College, late Professor of Mathematics, Yorkshire College of Science, now Professor of Geology, Oxford; Arthur Ransome, M.D., F.R.S., First-class Natural Sciences Tripos, 1856, Physician to the Manchester Hospital for Consumption and Diseases of the Throat; and George John Romanes, F.R.S., Sir Robert Rede's lecturer, 1883, late Professor of Physiology in the Royal Institution of Great Britain.

AN important conference on technical education was held at Newcastle on Saturday. It was summoned by the Technical Education Committee of the Northumberland County Council. Sir M. White Ridley, the Chairman of the Council, said that the scheme of the Technical Education Committee, generally speaking, had opened out two progressive educational roads from the elementary day school onward-first, for day scholars, by means of scholarships; and secondly, for evening students by a graduated system of classes. The work in progress under that scheme had already been very extensive. As regarded agricul ture, there had been courses of lectures on manuring land, poultry-keeping, farm stock, dairy work, &c. Educational courses had been given in mining, mechanics, electricity, engineering, ship building, &c. As regarded the fishermen also, a very successful method had been adopted of teaching the men a few plain scientific facts with regard to coastal navigation, the habits of fishes, and so on. After the delivery of the Chairman's speech the Committee's scheme was carefully discussed.

PRIZES and certificates in connection with the City and Guilds of London Institute will be presented on Monday, December 12, at Merchant Taylors' Hall, Threadneedle-street, by Mr. William Anderson, F.R.S The Lord Mayor will preside.

AT the General Monthly Meeting of the Royal Institution on Monday, the special thanks of the members were returned to Mr. Ludwig Mond for a donation to the fund for carrying on investigations on liquid oxygen.

MR. STREETER held a reception on Saturday at 18 New Bond Street for the first display of sapphires from the Montana mines. At the same time an assortment of chrysoprase jewels was exhibited, and also a black diamond, said to be the largest yet discovered. Mr. Streeter also showed, among other things, a collection of different specimens of pearl-bearing oyster shell, and some curious formations of pearls in shell and loose, and in a variety of natural colours.

IN the current number of the Geological Magazine it is noted that Mr. Joseph E. Carne, Curator of the Mining and Geological Museum, Sydney, New South Wales, who so ably assisted the late Mr. C. S. Wilkinson during the Mining and Metallurgical Exhibition at the Crystal Palace, Sydenham, in 1890, has been appointed by the Minister of Mines to the post of Geological

Surveyor. Mr. Carne entered the service of the New y Wales Government in 1879.

THE French Association for the Advancement of Science received from an anonymous donor the sum of 600 francs, : given in two prizes (of 400 and 200 francs), to the author the best memoirs containing an investigation, according to documents, of the frequency of rabies, and the prophyl measures in operation in a department of France, a excepted, or in a region (two or three departments) of France of Algeria. The statistical figures must relate to ten years least, and comprise the results of 1892. Manuscripts to her to the secretary in Paris before March 31, 1893. The foll points are noted for investigation :-The number of animals, of dogs, of persons bitten, and dead through r also of those vaccinated at the Pasteur Institute; separate cases of rabies in large towns from those in the rest of department; measures of sanitary police, their effect and culty of application; causes of more or less frequency of m and of vaccination; measures taken in frontier departmects DR. B. PASQUALE has undertaken a study of the phezor and causes of the very destructive disease of the vine kan mal nero," his observations having been made chiefly in S The disease makes its appearance in the form of black and streaks on the leaves. Dr. Pasquale finds it to be a accompanied by a Schizomycete, which he believes also: its cause, and which is parasitic, especially on the tissues to protoplasm and in other plastic substances, such as the cambr the medullary rays, the cortical parenchyma, and the soft ba the axile organs.

64

THE Botanical Gazette states that, in a report to the Com University, Prof. L. H. Bailey firmly establishes the comm value of the electric light for certain winter crops, especia lettuce. Certain kinds of plants, which are injured by the rays of the light, are not injured, but may even be here when the light passes through a clear glass globe or thro glass roof. Auxanometric records appear to show that the accelerates growth, but does not change its normal perio This is in harmony with the observations of Prof. G. Bonne corded in the Comptes rendus, who finds that the electric promotes the formation of chlorophyll in all kinds of both woody and herbaceous.

THE third appendix, 1892, of the Kew Bulletin bis issued. It consists of a list of the staffs of the Royal Gr Kew, and of botanical departments and establishments at ho and in India and the colonies, in correspondence with Kes

M. EDOUARD BRANLY, Professor of Physics at th Libre des hautes études, Paris, writes to us to compli experiments made by him are attributed to Mr. Dawson 7 in our account of " Physics at the British Association (NA August 18, p. 384). We learn that in Mr. Turner's pape in the condensed report furnished by him for publicata f. justice was done to Prof. Branly's work. The reference to Branly was unintentionally omitted when the report was cut down for NATURE.

MESSRS. MACMILLAN & Co. will publish immediately book by Professor Oliver Lodge, entitled "The Pio Science." In this volume, which will be fully illustratio portraits and diagrams, the author describes in popular the history and progress of Astronomy. His aim has state scientific facts and laws as simply as possible, to pres turn a living figure of each Pioneer, and to trace his on the progress of thought.

DURING the past week barometric depressions have s our western coasts with considerable frequency. As

urbances were passing away from our islands, sharp frosts ccurred in the north, where the shade temperature fell as low 13° in the north of Scotland on Thursday, December 1. The les which accompanied the depressions were confined more irticularly to the north and west. On Saturday, the 3rd stant, a large cyclonic disturbance appeared from off the tlantic, and in the rear of this cold north-westerly winds set with snow or hail showers generally; in many parts of the untry the snow was sufficiently heavy to interfere seriously ith traffic. The temperature continued to decrease, the ghest daily maxima being generally below the average for the ne of year, and at places in the north and north-east of our lands the maximum thermometer at times did not rise above e freezing point. For the week ended the 3rd instant the ficial reports show that the rainfall was greatly in excess in cotland, and rather so in the south of England and some of

e western districts; but in the eastern parts of Great Britain, id in the north of Ireland, there was a deficiency. In the uth-west of England the deficiency, from the beginning of the ar, is still very great, being 22 per cent. of the average

nount.

MR. H. C. RUSSELL, in his presidential address to the Royal ociety of New South Wales, mentions a very curious drift of a current bottle" thrown from the Austrian man-of-war Saida, out half-way between Sydney and New Zealand. This bottle and its way through twelve degrees of latitude and four of ngitude to the coast of Australia, two miles north of Tweed ver, where it was found just eleven months after it was own into the sea. Mr. Russell states that from what is own of the currents, which set strongly to the south along the ast of Australia, it seems impossible that it could have velled direct, and that it was therefore probably carried eastird to the coast of New Zealand, and thence northward wards New Caledonia, until it got into the current setting om there to the coast of Australia; a journey of at least 500 miles in 335 days, and doubtless subject to many deviations ich made its course longer and all the more surprising. M. W. PRINZ, Secretary of the Belgian Microscopical Society, s published an interesting paper on filiform inclusions in the artz of St. Denis, Mons, which strangely simulate organic uctures. He has at the same time discussed the origin of ss agates, and has repeated the experiments with colloid ca and certain salts by which very similar appearances are duced. The paper, which is illustrated with a plate, is a uable contribution to the literature of a very interesting oject.

MR. W. HOLLAND contributes to the December number of the tomologists' Monthly Magazine some good practical hints on aring. Moths, he says, often come more readily when sugar pplied to the twigs and branches of the trees they feed upon, wigs of something near their food-plant, than they will to ar placed on the trunks of trees; Xanthic citrago, for ance, will hardly come at all to sugar put on the trunk of the : tree; an occasional one only will be got in this way, but ugaring below the tips of the outermost branches all round tree Mr. Holland generally finds about fifty on one tree, des other species. In the case of Xanthia aurago again, best place to sugar is along the outside of the beech wood ath the ends of the overhanging branches, or on the s of the hedge below them. Mr. Holland has repeatedly n about 100 in a night in this way, when trunks sugared e and outside the wood have not yielded one specimen. er things may be got in the same way by selecting the place rding to the species wanted. Among other points to which ills attention is the necessity of recognizing early what is to be a species of the year, for every year brings some

The sugar Mr. This is very

particular kind more plentifully than usual. Holland uses is "Egyptian raw," a date sugar. dark and strong stuff, sand-like, and free from lumps, and it mixes easily without boiling. He simply mixes it with beer, and then adds a drop or two of essence of pears just before starting out. There is rum enough in good sugar, and to add more is only to make the moths drop off before they can be bagged. "Jamaica foots" is a good sugar too, but it is lumpy and needs boiling. Old black treacle will do fairly well as a bait, but "golden syrup" Mr. Holland believes to be a fraud. Beetroot sugars, or refined sugars, are of course bad, and if he happens to be in a place where he can get only these, then, and then only, he adds rum.

THE second volume of the Transactions of the Leeds Naturalists'

Club, to which we referred last week, includes an interesting paper on the structure and life-history of a fungus, by Mr. Harold Wager, assistant lecturer and demonstrator in biology, in the Yorkshire College, Victoria University. The paper deals with a small microscopic fungus, Peronospora parasitica, as a type of the fungi. Mr. Wager points out that, although in some respects this may not be the best type for the purpose, it has the advantage of having a comparatively simple structure and method of development easy to understand, and serving as an excellent introduction to the morphological study of the fungi. This type is also the more interesting because many structural details, which are fully described by Mr. Wager, have been more fully worked out in it than in any other. The paper is carefully illustrated, and the author gives a useful summary of the methods employed in the examination of the various structures he mentions.

A NOVEL utilization of aluminium is that for the construction of aluminium slate-pencils. Major von Sillich, of Meiningen, found that aluminium gives a stroke on a slate, and a German company has undertaken the manufacture of pencils based on that fact. They are 5mm. thick and 14mm. long. They need no pointing, and are well-nigh inexhaustible and unbreakable. The writing, which is as clear as with ordinary pencils, requires a little more pressure. It can be erased with a wet sponge.

solution with a standard solution has been constructed by A COLORIMETER for comparing the intensity of colour in a Papasogli. It consists of two graduated cylindrical vessels of equal diameter, through which light is transmitted from below. A vertical telescope fixed above the tubes shows the two halves of the field equally illuminated if the amounts of coloration are the same. If they are not, the heights of the liquids in the tubes can by a simple contrivance be so regulated that the colours have equal shades. Under these conditions, the concentration of colouring matter is inversely proportional to the length of the column of liquid tested.

THE Trinidad Field Naturalists' Club has held its first annual meeting, and has evidently good reason to congratulate itself on its success, which has surpassed the highest expectations of the members. Mr. Caracciolo, the chairman, in his

presidential address, reminded the club that the gardens, plains, mountains, and rivers of Trinidad swarm with animal forms, about a good many of which very little is yet known.

THE latest instalment of the Transactions of the Institution of Engineers and Shipbuilders in Scotland includes the address by Mr. Robert Dundas, president, at the opening of the present session. Speaking of railways, Mr. Dundas said that a continual improvement in rolling stock generally can be noted. Larger and more commodious carriages are gradually taking the place of the smaller ones, and there is a marked increase in the application of the bogie principle, which does well, and makes an easy running carriage when properly constructed.

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