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reject Brongniart's idea of its possible affinity to the Marsileæ, inclining to the belief that it approached nearer to the Coniferæ, and especially to Salisburia. This impression they retained when, at a later date, they described a second species of the same genus.

In his "Tableau des Genres de Végétaux Fossiles," published in 1849, Brongniart returns to the subject. He here calls attention to the readiness with which Sphenophyllum may be confounded with the genus Asterophyllites, which some forms of the former genus closely resemble; but he again repeats that the two can be distinguished by the fact that in the former genus the leaves never exceed ten in number, whilst their form is triangular with a truncated summit. He again dwells upon the fact that in some Sphenophylla the leaves become so deeply lobed, narrow, and linear, as to be easily mistaken for those of Asterophyllites. He now affirms that the fructification is closely related to that of Asterophyllites.

As to the affinities of Sphenophyllum, Brongniart now asks, "Does the plant combine the leaves of a Marsilea with the verticillate of an Equisetum, or is it a Gymnospermous Phanerogam, the leaves of which approach those of the Gingko?" He does not answer the question, but concludes that this cannot be done until the fructification of the plant is better understood.

In 1864 a monograph on the species of the genus was published by M. Eugene Coemans and M. J. Kickz; but the authors make no serious effort to solve the vexed question of the affinities of the genus.

We now enter upon a new stage in the history of the genus. In 1870, M. Renault presented an important memoir to the French Academy of Science, which, for the first time, threw light upon the internal organization, especially of the stems, of Sphenophyllum. He described two examples, one from Autun and the other from St. Etienne, both of which exhibited a structure wholly different from that of any plant previously known, recent or fossil. In the centre of each stem was a primary vascular bundle, the transverse section of which was a triangle with three concave sides and three prolonged, narrow, intermediate arms. This axial organ underwent no subsequent growth after its first formation. But it was invested by a secondary zone, which was deposited upon the primary triangle layer after layer like a secondary xylem, producing a circular axis, which enlarged as the plant advanced in age. But this secondary growth did not consist of layers of vessels, but of vertical columns of thick-walled cubical cells. cortex also exhibited specially distinctive features. These discoveries made it clear that Sphenophyllum constituted, not only a very distinct genus, but a type of plant far removed from everything previously described.

The

It fell to my lot to make the next advances in our knowledge of this genus. In 1871 I described in the memoirs of the Literary and Philosophical Society of Manchester a new fructification, to which further reference will be made later on. In 1872 I obtained from the Oldham deposits some new stems which obviously belonged to the same type as those discovered by M. Renault, but from which they differed in important points of detail. These were described in my Memoir, Part V., published in the Philosophical Transactions for 1874. Transverse sections of these closely resembled in their dominant features M. Renault's corresponding ones, but with two differences. When my plants attained to a certain stage of their exogenous growth, a well-defined circular boundary marked a temporary arrest of that growth, but which started afresh from a zone of much smaller vessels (loc. cit. Pl. II., Figs. 11 and 12), that increased in size as the diameter of the axis increased, as they had previously done in the more internal series. Still greater and more important differences presented themselves in the longitudinal sections.

The zones of secondary or exogenously developed xylem, which in M. Renault's examples consisted solely of verticolumns of thick-walled, cubical cells, were composed, in mine, of true tracheidal vessels with reticulated (not with bordered pits) walls; presumably a higher stage of development. Another new and more advanced feature than characterise Renault's cells, seen best in tangential sections of this zone (loc. cit. Fig. 13), was the existence, between contiguous tracheids, of vertical, but interrupted, series of small cells, which I can only regard as rudimentary medullary rays. In the same memoir (loc. cit. Pl. IV.) a still more distinct form from the Burntisland deposits in Fifeshire was figured and described. M. Renault and Count Solms Laubach refuse to recognize a Sphenophyllum in this type, but they have not yet convinced me that I am in error on the point. The fact is that, though widely aberrant from the form described above, it scarcely differs more from that form than the latter does from M. Renault's examples.

But my Oldham specimens raised another debated question. When the Memoir V. was published, all authorities agreed that the maximum number of true leaves in each verticil was ten or twelve; that, however deeply subdivided, their outline was a sphenoid one, anc not linear, and that they were multinerved. But I am still convinced that in my specimens there were more than twenty such leaves; that they were linear in outline, and had a single median nerve. It followed that, continuing to accept the existing definitions of the genus Sphenophyllum, my plant was Asterophylloid rather than Sphenophylloid. I am now prepared to admit that it is a Sphenophyllum; but only on the condition that we alter our definitions of the latter genus, and admit the possibility that some of the forms may possess twenty or more undivided and linear leaves. The accumulating evidence that the foliage of at least some of the Sphenophylla was dimorphic makes the acceptance of my proposition a matter of necessity.

Yet more recent researches have revealed new and important facts connected with the history of these plants. I have already alluded to the new fructification which I described in 1871, and to which I gave the name of Volkmannia Dawsoni. M. Renault's memoir already noticed was laid before the French Academy in May 1870, and noticed in the Comptes Rendus of that date; but owing to accidents growing out of the Siege of Paris, it was not published until three years later. Mean

while my

memoir on Volkmannia Dawsoni was published, and a copy of it forwarded to M. Brongniart. After giving details of the structure of the strobilus I arrived at the conclusion that "it is the fruit either of Asterophyllites or of Sphenophyllum."

Two years later M. Renault's memoir of 1870 was combined with a second one on the same subject, and published. It contained a note by M. Brongniart, referring to my memoir of 1871, in which note he says, "This work agrees in many important points with the results obtained a year previously by M. Renault, though Mr. Williamson was unacquainted with the article in the Comptes Rendus of May 30, 1870. The fossil plant studied by Mr. Williamson, and named by him Volkmannia Dawsoni, doubtless differs, at least specifically, from that described by M. Renault, by the form of the central vascular bundle, and by the absence of the zones of quadrangular cells which surround it in the French specimens; cells which in consequence of the thickness of their walls would not be readily destroyed.”1

1 M. Brongniart has here failed to comprehend an important point. The cells, the absence of which he notices, really belonged to the secondary xylem of the older stem, which did not become developed in the youngest twigs. But it was only upon these twigs that the fructifications were formed, and of which they were but extensions. Hence their absence was merely a consequence of difference of age, and not a feature of specific

value.

In 1890 I figured in my Memoir XVIII. (Phil. Trans. 1890) a transverse section of what was obviously a stem of Bowmanites Dawsoni, in which the primary triangular axis of the strobilus was invested by a thick zone of the secondary xylem. So far as the arrangement of its tissues is concerned this stem is constructed on exactly the same plan as appears in M. Renault's and my own Sphenophylla. In describing it I further said, "We must unite Sphenophyllum with some forms of Asterophyllites in the same genus. It is equally clear that Bowmanites, though its peculiar fructification demonstrates that it constitutes a perfectly distinct genus, has strongly marked features of affinity in the structure of its stem to the Sphenophylloid type."

The above reference to differences between the fructification of Bowmanites and of Sphenophyllum were based upon the minute description of the fruits of the latter plant, published by M. Renault ("Etudes sur le Terrain Houiller de Commentry," pp. 481-2). Those descriptions differ widely from what exists in my Bowmanites, but M. Renault distinctly identifies them with the fructification of Sphenophyllum. I obtained additional and important specimens of Bowmanites in 1890, which threw much new light upon its organization, and which were recorded in my Memoir XVIII. (Phil. Trans. 1891).

In July last an important communication was laid before the Academy of Sciences by my friend M. Zeiller, the distinguished director of the Superior National School of Mines at Paris. In it he records his identification of a fructification of a Sphenophyllum of the type of S. pusillum of Sternberg and S. erosum of Lindley and Hutton, with my Bowmanites Dawsoni. If this determination is correct, and I see no reason for doubting that it is so, we now have some more definite facts than we have hitherto possessed, guiding us alike in identifying the true fructification of Sphenophyllum and in determining its position in the vegetable kingdom.

Before explaining M. Zeiller's observations more in detail, a few words explanatory of the structure of Bowmanites will make M. Zeiller's views more intelligible to the reader.

The accompanying diagram represents two nodes and

overlapping from two to three internodes. From the upper surface of the disk numerous slender sporangiophores (e) spring, each one proceeding upwards and outwards, to become attached to the upper or distal extremity of a large oval sporangium (ƒ). Each of these sporangiophores has running through it a small bundle of barred tracheids, which terminate at the point of attachment to the sporangium. Each tracheal bundle is a prolongation of one of a circle of similar ones that ascend from the central axis into the disks. These fructifications, besides being manifestly eusporangiate, are extremely characteristic of the plant, nothing identical with them having been observed by any of the authors who have investigated the Carboniferous strobili. After these illustrations I will allow M. Zeiller to explain his views in his own words. After referring to the details given in my Memoir XVIII., M. Zeiller says:"L'aspect de ces sporanges, ainsi attachés au bout de ces pédicelles recourbés, est exactement, à part les dimensions moindres, celui de sporocarpes de Marsilea. L'analogie parait du reste n'être pas purement superficielle; M. Williamson a reconnu en effet, dans le pedicelle de chaque sporange, un cordon vasculaire bien caractérisé, qui prouve qu'on n'a pas affaire là à une simple formation épidermique, comme pour les sporanges de Fougères ou de Lycopodinées. Il faut, à ce qu'il semble, regarder ces pédicelles comme représentant des lobes ventraux des bractées, analogues au lobe fertile des frondes d'Ophioglossées, ou à ceux des Marsiliacées ; seulement ils portent à leur extrémité non pas une série de sporanges comme chez les premières, ou plusieurs sores comme chez ces dernières, mais un sporange unique à paroi formée d'une seule assise de cellules."

"De cette constitution des épis du Sphen. cuneifolium' il report que, si les Sphenophyllum rappellent les Lycopodinées par la structure de leur axe, ils s'en éloignent notablement par la disposition toute spéciale de leur appareil fructificateur, qui tend à les rapprocher plutôt des Rhizocarpées, et qu'ils doivent donc bien décidément être considéré comme formant une classe distincte parmi les Cryptogames vasculaires."" Agreeing thoroughly with these conclusions further comments are needless. WM. CRAWFORD WILLIAMSON.

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one internode from a vertical section of this fruit, with the sporangia and three sporangiophores in situ.

So far as external contours are concerned, it is undistinguishable from many of the true Calamarian forms of fructification. It is only when cut into sections that its characteristics can be discovered. Its central axis (a) has nodes (6) at short and regular intervals, and at each node is a verticil of from 16 to 20 sporophylles or fertile bracts (c). At their basal portions these bracts are coalesced into a lenticular disk (d), from the margin of which the thinner and narrowing bracts extend upwards,

THE

DENDRITIC FORMS.

HE curious appearances presented by certain native specimens of silica have been observed for so long, that it is somewhat surprising that so little is known about their real constitution and mode of formation.

Rock-crystal is frequently found to contain bubbles of liquid, usually either water, carbon dioxide, or petroleum, or crystals, such as scales of mica, forming aventurine, and fibres, such as asbestos, forming cat's-eye. More rarely, however, forms of apparently vegetable origin are seen; one of the most remarkable specimens is a prolate spheroid, about five inches long and four inches across, cut from a clear colourless rock-crystal, in which are embedded numerous fragments about the size of a large pea, presenting the exact appearance of club-moss.

Agate is frequently found with distinct coloured layers, either flat or distorted, and usually milk-white, red, brown, or black. It is then known as onyx.

More rarely, agates are found with markings like moss or foliage distributed through them; they are then known as moss-agates, or Mocha stones.

In 1814, Dr. J. MacCulloch described some cryptogamic forms in the agates of Dunglas (Geological Trans., ii.,

The species of Sphenophyllum to which M. Zeiller's strobili were attached. 2 Comptes Rendus des Séances de l'Académie des Sciences, Paris, July 11, 1892.

iv., 398). It is stated that the Earl of Powys possesses an onyx containing the chrysalis of a moth.

It seems to be generally assumed, without any strong evidence, that rock-crystal and agate have been formed from solution in water, possibly superheated, and that in such cases as those mentioned above, various crystalline or fibrous minerals and low forms of plant life have been inclosed during the process of solidification.

Though this explanation is very possibly true in many cases, it does not account for all the appearances seen in moss-agates; and another possible mode of formation ay be suggested by a brief account of some experiments made more than twenty years ago.

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Ordinary crystals of ferrous sulphate dissolve readily in cold water; but if they are placed in a dilute solution of an alkaline silicate, an entirely new series of phenomena are produced, which were first described by J. D. Heaton, M.D., in a paper On certain Simulations of Vegetable Growths by Mineral Substances" (Brit. Assoc. Report, 1867, p. 83). On immersing crystals of ferrous sulphate in a solution of sodium silicate of the density 1065, very beautiful arborizations will soon begin to shoot perpendicularly upwards, attaining the height of three or four inches in a few hours. In a weaker solution roots can be caused to shoot downwards from a suspended crystal. The fibres contain silica and iron (less the weaker the solution); they are brittle, and more dense than the liquid in which they are formed. Examined by the microscope, the ultimate ramifications are cylindrical, tapering tubes, the walls of which are granular, showing no sign of crystallization. The roots are more abrupt and occasionally club-shaped in their terminations. The growth is interstitial like that of organized living tissue. "Supposing such purely mineral substances to have been formed in by-gone geological eras, and to have been accidentally fossilized in some primary or other ancient rock, they would very probably, when discovered by recent investigation, be pronounced to be an evidence of organized beings having existed contemporaneously with the formation of such rock."

In the following year a similar observation was made by Prof. W. C. Roberts-Austen (J. C. S., 1868, xxi, 274). A solution containing 49 per cent. of silica, when allowed to gelatinize, and dried for two days over sulphuric acid, left a solid residue similar to opal from Zimapan, but containing 214 per cent. of water. All the specimens of jelly dried in air contained dendritic forms, varying in size from o'2 to 05 mm. When magnified 90 times they appeared as radiating fibres; when the power was increased to 700 times linear, each fibre resolved itself into a series of elongated beaded cells with clusters of circular cells at intervals. Mr. Slack indicated their remarkable analogy to common blue mould or mildew. The cells appeared to be hollow, and did not blacken with sulphuric acid.

A few years later I repeated Dr. Heaton's experiments,

and made some additional ones, a brief account of which

may induce some one with better means at his disposal to investigate an interesting and somewhat neglected subject.

If a crystal of copper sulphate be suspended in a solution of potassium silicate, which has been carefully neutralized and has a density of 1065, in the course of a few minutes a hollow green column will be seen to run down from the crystal to the bottom of the beaker. Sodium silicate may be used instead of potassium silicate, but the appearance and rapidity of the growth is somewhat changed. The solution may be neutralized with hydrogen sulphate, chloride, or acetate, but hydrogen fluoride appears to prevent all growth. If the solution has a density less than 106, no growth occurs, and the crystals generally dissolve; the weaker the solution down to this limit the more rapid the growth. If the solution be stronger, the time required for the growth to com

mence may be lengthened from minutes to many day If the density be above 125, no growth takes place. Copper sulphate gives the best results, but it may b replaced by ferrous, manganous, or nickel sulphate; wit changes in the shape, and of course in the colour, of th growths. The growths take place most readily from clean sharp crystal, and always from an angle or edge an edge obtained by cleavage requires more time. Othe salts besides the sulphates may be used, but do not a so rapidly, probably owing to less perfect crystallizatio of the specimens used.

In a neutral or very feebly alkaline solution the growth are comparatively rapid, and consist of long, branchin tapering fibres, not unlike the roots of a tree. The grow rather more rapidly downwards than upwards. the solutions be decidedly alkaline, the growths are muc slower, and consist of fine stalks with comparatively larg lumps at the extremities.

The tubes seem to be composed of silica with a sma proportion of the metal used; they differ much in colou are more dense than the liquid in which they grow, az are insoluble in water or dilute acids. When magnife 100 times, the substance of the tube shows no appearanc of crystalline form, but seems to consist of concretion of ovoid granules. In this particular it differs from th substance of lead or silver trees, and from the curio fibres of potassium, iodide, and chloride described b Mr. Warington (J. C. S., v., 136, viii., 31).

It is generally assumed that the formation of onyx i due to the successive deposition of layers of silica coloured by different substances, but the following ex periment suggests another possible method of formation especially when the extreme permeability of gelatinou silica by liquids is remembered. So readily are ever the hardest agates permeated by hot aqueous solution of salts, that "staining" is a common commercia process.

A little too much sulphuric acid was accidentally added to a moderately strong solution of potassium silicate in which some crystals of copper sulphate were lying. The copper sulphate dissolved, and the solution set to a uniform blue jelly. After standing for about a week, the blue colour at the top of the jelly had separated into a series of thin parallel coloured plates, leaving the jel between them colourless. This curious separation of the colouring-matter gradually proceeded downwards, and reached the bottom of the precipitating glass in about a month. The jelly gradually shrank, dried, and hardened. forming fragments consisting of blue bands in a white SYDNEY LUPTON.

mass.

NOTES.

THERE will be a memorial celebration for A. W. von H mann on November 12, arranged by the Deutsche Chemische Gesellschaft, at Berlin on the 25th anniversary of its foundation. The Empress Frederick and many German and foreign cele brities have been invited to be present. The proceedings, which will take place at the Berlin Town Hall, will include speeches on the history of the Society and on Hofmann, a review of pre gress in chemical science by Hr. Wislicenus, and choral music, performed by the members of the cathedral choir.

WE regret to have to record the death of Mr. Robert Grast F.R.S., Professor of Practical Astronomy at the University Glasgow. He died at Grantown-on-Spey, his native place, a the age of seventy-eight.

THE death of Dr. Löwenherz, director of the Imperi Physical Institute, Berlin, has been announced. He died a

Berlin on Sunday last.

PROF. VIRCHоw has been appointed an honorary membe of the Imperial Russian Natural Philosophy Society.

AN international ethnographical exhibition is to be held next year in St. Petersburg. It will be organized by the Russian Geographical Society.

THE American Microscopical Society offers prizes for the encouragement of microscopical research, two of the value of 50 dollars each, and two of the value of 25 dollars each, for the best papers which shall give the results of an original investigation made with the microscope, and relating to animal and plant life respectively; also two of the value of 30 and 15 dollars respectively for the best six photomicrographs in some subject of animal or vegetable histology; and two of the same value for the best collections of six mounted slides illustrating some one biological subject.

IN a letter to the Times on scientific titles and their abuse Prof. Tilden has opened a subject of considerable interest to men of science. It is well known that the letters indicating membership of a society are sometimes used by persons who have no right to use them, and Prof. Tilden notes that an effort is to be made to deal with this evil by getting a Bill before Parliament "for the purpose of securing to the respective societies the copyright of these letters." This, however, is a comparatively unimportant aspect of the question. The real difficulty is that membership of scientific societies is frequently "represented in courts of law or by candidates for public appointments as evidence of professional trustworthiness," whereas in very many cases it does not at all necessarily imply any extensive or accurate knowledge of the subjects in which the societies are especially interested. "Fellowship of the Royal Society, indicated by the letters F. R. S.," says Prof. Tilden, "is a real distinction which is justly prized. But what is the public to understand regarding such alliterations as F. B.S., F.C.S., F. E. S., F. G. S., F. L. S., F.S.S., F.Z. S., and of F. S. A., M. R. I., F. R. A. S., F. R. M. S., F. R. G. S., F. R.S. E., &c. ? With the exception of one or two of the societies represented here, admission is to be gained by almost any one who is willing to pay the customary contribution to the funds of the society, and who can get two or more members of the society to testify to his fitness for admission, which generally means respectability and a profession of interest in the subject, the cultivation of which is the object of the society." He adds that if the public knew all about the societies no harm would arise; but "judges and barristers, and county councillors and town councillors cannot be expected to have this knowledge." Prof. Tilden thinks that "the only chance for a better state of things is for every member of these societies who respects himself to abandon the use of these unmeaning letters altogether"; but he fears that there is very little prospect of such a general reform while "an Institute having for its president no less a person than the Heir Apparent to the throne condescends to bait its advertisements for subscribers with the offer of more letters. The Times, discussing the subject in a leading article, expresses the opinion that in the main "we must trust, imperfect though the security is, to the ability of grown-up men and women to protect themselves against a form of deception which has most hold over those who themselves covet the meaningless letters to which they blindly pin their faith."

THE weather during the past week has been characterized by a marked increase of temperature and excessive rainfall, accom. panied by strong southerly winds and gales. Between Wednesday the 26th and Friday the 28th October, the temperature in parts of England increased upwards of 30°, while the air became very humid and unpleasant. The continuance of comparatively high temperature, during which the thermometer reached 60° in the central and southern parts of the kingdom, was due to the track of the depressions, causing a continual indraught of warm air from off the Atlantic. On Thursday the 27th ult., about 1

inch of rain was measured in the West of Ireland, and heavy falls occurred on the following days in the Midland counties. A further downpour, amounting to 1 inch in the Channel Islands, and to 1.3 inch in London, occurred on Sunday night,

and the amount which has fallen on the east coast of Norfolk

during the month of October is about equal to three times the average. During the first part of the present week, the disturbance which caused the heavy rainfall passed away, and a small area of high pressure temporarily advanced over the United Kingdom from the Atlantic, while the temperature fell several degrees, with mist or fog in places; but conditions were very unsettled, and a change of wind to the south-eastward in Ireland gave indications of probable further disturbances. During the week ended the 29th ultimo, the amount of bright sunshine exceeded the mean in nearly all districts.

THE Meteorological Council have recently issued a summary of the Weekly Weather Report for the quarter ending September 1892. which shows the rainfall and mean temperature in each district for each similar quarter for the twenty-seven years 1866–92, grouped in five yearly averages, and also the means for individual years from 1881. The average rainfall of the quarter for the whole of the British Islands was 10'2 inches, or only o'7 inch in excess of the mean for the whole period. This result is almost entirely due to an excess in the grazing or western districts, amounting to 15 inch, while in the wheat-producing or eastern districts the fall for the quarter is slightly below he mean. The temperature for the quarter has been below the mean generally; for the whole of the country the deficiency amounted to 1°8, and was 1°.7 in the grazing districts and 1°9 in the wheat-producing districts. Similar returns show that the excess of rainfall amounted to 15 inch in the same quarter of 1891, prior to which there had been a series of seven dry quarters, while the temperature has been uniformly below the mean for six corresponding quarters. The coldest quarter was in 1888, when the deficiency amounted to 2o5, this being, in fact, the coldest corresponding quarter during the last twenty-seven years.

THE late Mr. George Grote, the historian of Greece, expressed in writing, eight years before his death, a desire that after his decease his cranium should be opened and his brain weighed and examined. The task was undertaken by the late Prof. John Marshall, and the results of his observations are set forth in a full report printed in the current number of the Journal what above the average in size, if compared with the adult male of Anatomy and Physiology. The entire encephalon was somebrain at all ages. If allowance be made for the effects of senile wasting, it must be regarded as a rather large brain, but not as an actually or especially large one. There can be no doubt, however, that it was, at death, further diminished in size and weight through the effects of disease, as shown by its marked deviation from the ordinary ratio as compared with the body. weight. As tested by the standard of macrocephaly adopted by Welcker, its utmost allowable weight was below that standard; and as contrasted with the encephala of certain other eminent men, it would find its place about one-third up from the lower end of the list. The general form of the cranium was rather or nearly brachycephalic, but it was decidedly higher than usual. The cerebrum itself was, in accordance with the shape of the cranium, short, broad, and deep. The cerebral convolutions were very massive, being not only broad and deep, but well folded, and marked with secondary sulci. This condition was observable all over the cerebrum, but chiefly remarkable in the frontal and parietal regions. Studied in reference to Dr. Ferrier's researches into the localization of function in the brain, the relative size of certain convolutions or groups of convolutions suggested some reflections as to individual peculiarities, but these reflections did not seem to Prof. Marshall

to be quite trustworthy. From the size and richness of the convolutions, the sufficiency of the grey matter both on the surface and in the interior of the hemispheres, and from the remarkable number of the white fibres, especially of the transverse commissural ones, the brain of Mr. Grote is pronounced to have been of very perfect and high organization.

THE method of cleaning mercury adopted at the Physikalischtechnische Reichsanstalt at Berlin is described in the Zeitschrift für Instrumentenkunde. The raw material is brought in iron bottles from Idria. It is filtered and dried, and twice distilled in a vacuum to get rid of the heavy metals. Great care is taken to eliminate fatty vapours derived from greased valves and cocks, which is accomplished by means of a mercury pump working without a stopcock. Finally, the electro-positive metals, such as zinc and the alkalies, are separated by electrolysis. The mercury is precipitated from a solution of mercurous nitrate obtained by the action of nitric acid on excess of mercury. The solution, together with the impure mercury acting as an anode, is contained in an outside glass vessel, into which a current from a Gülcher thermopile is conducted by an insulated platinum rod. The cathode rod dips into an interior shallow glass vessel, in which the pure mercury is collected. On careful analysis it was found that no perceptible non-volatile residue was left by 200 grammes of the purified metal. Thus the mercury is well fit for use in standard barometers and resistances.

THE results obtained from the botanical work done at the various experiment stations in the United States will in future be published in the form of an "Experiment Station Record," issued by the Department of Agriculture, under the editorship of Mr. Walter H. Evans.

ANGLO-INDIAN papers record the presentation of an interesting "piece of architecture" to the Madras Central Museum by Lord Wenlock. It is a hornets' nest, belonging probably to the species Vespa cincta. It is conical in shape, and is constructed of a material resembling rough paper or cardboard composed of woody portions of plants gummed up by the insects, and brought into the condition of paste by means of a viscid salivary secretion. The combs are placed in tiers and attached to each other by small columns of the same paper-like material of which the nest is composed. It is two feet in height, and about the same in

circumference at the base. It was obtained in the course of one

of His Excellency's tours.

M. DE NADAILLAC, in the current number of La Nature, discusses the significance of some of the facts which have been brought to light by the recent excavations of mounds in the Ohio Valley. The mound builders knew how to construct earth fortifications, which were of considerable extent and always remarkably adapted to the sites chosen. They buried their dead under tumuli of astonishing dimensions. Copper was the only metal they could work, and they undertook long journeys in search of it. Their weapons and implements were of stone. They made vases of pottery, and were able to produce representations of the human figure and of animals, both by sculp turing them in stone and by modelling them in clay. At least in some districts they were sedentary, and, like all sedentary populations, they had to obtain the means of subsistence in part by cultivation of the soil. They were often engaged in fighting, and numerous burials in which the bodies are crowded together bear witness to the fury of their struggles. Whence did they come and who are their descendants? M. de Nadaillac thinks that these questions can never be definitely answered unless investigators discover some traces of the language of the moundbuilders.

WITH regard to the revival of animals after exposure to great cold, Herr Kochs (in the Biologisches Centralblatt) points out two things which retard formation of ice in the animal body. First, the body does not contain pure water, but salt and albumen solutions, which only freeze under zero C. Then capillarity and adhesion hinder freezing. Herr Kochs states that water in a glass tube of 0.3 to 0'4 mm. diameter may be cooled to -7° and even -10° C. without freezing. With a diameter of only o'r to o'2 mm. the water is not frozen, even though the end of the tube be put in freezing liquid. Thin liquid sheets between two glass plates behave in the same.way. If a salt solution freezes, the salts are excluded; and pure water, in freezing, gets rid of its absorbed gas. Fresh blood, according to the author's experiments, freezes only after being strongly cooled to -15°C., and after complete elimination of gases and salts. The blood corpuscles are dissolved and the blood loses colour. The same elimination doubtless occurs in freezing of protoplasm. Ex-Ophthalmology at the last annual meeting of the British Medical periments cited to show the possibility of “anabiosis" may probably be explained by the decomposition process not having gone so far as to bring life completely to a standstill. Similar results were obtained in experiments on drying of seeds and various animals. It was shown with what tenacity many animals, under most unfavourable circumstances, retain the moisture necessary to life.

THE very destructive American disease of the vine known as the "Black-rot" has, for some years past, made its appearance in Europe, and its life-history has now been thoroughly investigated by Viala, Ráthay, and others. The ravages of the disease have been traced to a parasitic fungus, Læstadia Bidwellii, the mycele of which develops in the interior of the organ attacked, chiefly the young branches and berries, and produces spermogones and pycnids in the course of the summer. It is especially by the pycnospores that the fungus is disseminated. Towards the end of the period of vegetation sclerotes are formed, usually within the pycnids, and the conidiophores spring from these. Peritheces are also formed in May and June on the fallen and infected berries of the previous year. Until recently the ravages of this pest in Europe were confined to the French vineyards, but it has recently been detected in Austria and in Italy. The most effectual remedy for it is salts of copper.

AN interesting and valuable paper on the association of shipping disasters with colour-blind and defective far-sighted sailors, read by Dr. T. H. Bickerton before the section of

Association, has been reprinted for the author from the British view of the prospects of legislation on this important question. Medical Journal. Dr. Bickerton takes anything but a hopeful He greatly fears that "many a shipping disaster will occur before the Royal Society's suggestions become part of the law of the land." Accordingly he urges all who interest themselves in the subject to abate not a tittle of their endeavours. "There are none," he says, "so difficult to convince as those who will not believe, and the men who have had the framing of the rules of the road at sea are the very men who hitherto have turned from all suggestions on the eyesight question with contempt. True it is that their language, judged from examples to be found in the Nautical Magazine, is becoming moderate, and even polite, but they lack knowledge of this subject, and they will still require our best attention." Meanwhile, Dr. Bickerton presses on the attention of the public the following facts:—that 4 per cent. of the whole male population are colour blind; that about 8 per cent. more have marked impairment of sight from refractive errors; that there is no official test whatever as to a sailor's eyesight; that a man may be the subject of any of the forms of eye disease, may have any degree of blindness, or may be so short-sighted as to be unable to see distinctly more than a few inches in front of his nose, and yet be at perfect liberty to be a sailor and to become an officer; and that, although there is a

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