tically continuous, in an outward direction, by the addition of layer after layer. The materials for the new vessels have obviously been furnished by some protoplasmic element which, whether we call it cambium, or choose to give it some other name, was located at the line of junction between the wood and the bark. The additions effected by its agency have gone on through successive ages until the thin vascular cylinder became a large hard-wooded stem capable of upholding a gigantic forest tree.

If we turn to the medullary rays, we find that they consist of vertical laminæ of cells. In the tangential section they appear as vertical lines of cells (f, Fig. 1, p. 490), undistinguishable from those seen in the corresponding sections of most conifers. In radial sections made in the plane of the medullary rays, we find that the latter proceed continuously from the pith to the investing bark, with each of which tissues they become intimately blended at their corresponding extremities. The component cells further exhibit, in this radial section, the mural arrangement so characteristic of ordinary medullary rays. As the vascular cylinder increased in diameter by additions to its exterior, so these medullary rays became lengthened by the similar addition of new cells to their outer extremities, such cells being supplied from the same source (cambium) as the corresponding new vessels.

Now, in all these processes of growth, I re-affirm that we

have nothing which can, in any plain sense of the word, be termed Acrogenous. I can discern no material difference between what I have just described and what occurs in a Cycad or in a Conifer. In all these cases the additions are equally made to the exterior of a gradually enlarging cylinder, new cells being added to the outer extremities of the medullary rays, and vessels to the intermediate lines of vascular tissues; the raw material for both having been furnished, as in exogens, by some protoplasmic layer located between the vascular cylinder and the bark. I do not very clearly understand what Dr. M'Nab means when he speaks of a "pseudo-exogenous" growth, or of an "increase which takes place in the wood cells of the primitive tissues, not, as in Dicotyledons, by additions to the woodcells of the fibro-vascular bundles." I detect no such difference as he seems to imply in the example which I have given.

If I rightly understand his meaning, Dr. M'Nab considers me to affirm that in all these cryptogamic plants of the coal-measures, there has been exactly the same process of growth, corresponding in each minute detail, as takes place during the growth of an oak tree. I have never affirmed this. On the contrary, I shall have to show that, amongst these coa plants, there are indications of many remarkable combinations and varied modifications of the process of growth.

Whether we do or do not accept the doctrine of evolution, we should expect to find such generalised combination amongst these primæval forms of vegetable life. I once more repeat, however, that these matters are scarcely capable of further discussion until my series of detailed memoirs has been published. When this takes place, I think Dr. M'Nab will see that I have not made the two "fatal errors" which he imagines I have done, and that there is more in my proposed classification than he, at present, has any idea of. At the same time I may remind him that the recognition of an exogenous process of growth amongst cryptogams is not now propounded for the first time. Dr. Hofmeister has given us most detailed accounts of such a process in his history of the development of Isoetes-itself a Lycopodiaceous plant. I merely propose to show that a mode of increment which now lingers in this one dwarfed genus amongst living Lycopodiacea, was once widely diffused, not only throughout this group of plants, but equally presented itself amongst the Calamitaceæ.

Prof. Dyer's temperate and intelligent reply to my article on the above subject resolves itself into two parts, the first of which deals with facts and the second with opinions. As to his facts he is in the same position as Dr. M'Nab. He is not acquainted with the materials for forming an opinion which I have in my hands, and upon which my views are based, consequently he has taken one extreme type of Lycopodiaceous stem, and made its supposed characters representative of the entire

group. No. 129 of the Proceedings of the Royal Society which contains an abstract of my last memoir on the subject, would have shown him that I do materially differ from Mr. Carruthers in my interpretation of Lepidodendron selaginoides, the plant to which he refers, which difference of opinion I also expressed at the Edinburgh meeting of the British Association. I there showed that the central axis does not, as Prof. Dyer affirms, "consist wholly of scalariform vessels," but that these vessels are largely intermingled with true scalariform cells. But this is not all. The plant in question is but one of a large variety of forms. It occupies one end of a linear series of types-the opposite extremity of which series exhibits a very different aspect. The medullary vessels, which, in Lepidodendron selaginoides, are thus intimately commingled with the medullary cellular tissue, in the other types gradually recede from the centre to the periphery of the central cellular axis; the latter thus assuming the condition of a purely cellular parenchymatous pith, the cells of which are not even scalariform. The medullary vessels, thus driven to the periphery, now assume the position of the medullary sheath of the higher exogens. The vascular tissues for which I claim an exogenous origin are superadded to the exterior of this vascular medullary cylinder. We thus see that the central axis of these plants, instead of consisting of two parts, as Prof. Dyer affirms, really consists of three, viz, a central cel

Stigmaria is an exception. In it the medullary vessels are altogether absent, as stated in my reply to Dr. M'Nab.

lular pith, an inner ring of vessels belonging to the medullary portion of the axis, and an external vascular cylinder, which grows by additions to its exterior, and which no more belongs to the central medulla than do the ordinary wood layers of an exogenous phanerogam. It has unquestionably been the product, as Prof. Dyer admits to be probable, of a cambium layer.

Speaking of the Lycopodiaceous stems of the coal measures, Prof. Dyer says, "I am inclined to think, with Prof. Williamson, that the stem increased in thickness." This point is not one to be thought about as if it was uncertain. We have in our museum accurate casts of the Dixonfold trees, and the base of the stem of the largest of these, above the point whence the huge roots are given off, is twelve feet in circumference! Higher up it is eight feet. There is surely no room for questioning an increase of thickness here, and this instance is but one example of what is sufficiently common in the coal measures. When we turn to the interior of these large trees, we find, as I have abundant evidence to prove, that they were enabled to sustain their huge bulk by an exogenous development of their outer cylinder of vessels, which were not mere modifications of the medullary vessels, but something superadded. This woody structure was amply provided with medullary rays, and each of the several layers of the thick bark increased pari passu with an increase of the ligneous zones, whilst a large cellular pith occupied the centre of the stem. So much for the facts, which are very different from those recognised by either of my two opponents. Now as to opinions, Prof. Dyer says he thinks that this increase was "nothing more than an incident in the lifehistory of a particular race of plants, nothing more than an adjustment to an arborescent habit dropped when the arborescent habit was lost." I am not sure that I understand all that Prof. Dyer means in this passage. He appears, however, to imply that these exogenous conditions were merely adventitious growths assumed for a season, and thrown off at the earliest opportunity; that they had no true affinity with the plants in which they were found. I confess I see no grounds for so remarkable a conclusion, especially remembering that, at least, these conditions lasted throughout the vast duration of the Devonian and Carboniferous ages. That one object of the exogenous growth was to enable these trees to sustain a huge superstructure, is doubtless true, though we find that growth in myriads of plants that have no such ponderous superstructures; but must we not say the same thing of the oak and the beech, as well as of the Lepidodendra? I see no difference between the cases. We have no more reason for regarding these conditions as merely an incident in the life-history of a particular race in the one instance than in the other.

I will not now discuss the value of the terms exogen and endogen, since the question has little importance in reference to the present object. I will only say that the mode of growth of a plant appears to me to have equal value with the mode of reproduction. There is a fashion in these matters-and in some circles there is now a tendency to elevate the reproductive at the expense of the vegetative, with which I do not agree, but I repeat this is not a question essentially important at present. My two great objects have been, first to demonstrate the existence of the exogenous structure in the trees in question; and second, to show the absurdity of applying the term acrogen to trees so constructed.

The value of my proposed classification is an independent question. I attach but a limited importance to the artificial boundary-lines introduced by systematisers, and do not wish to assign more to my own than to those of others; nevertheless, such divisions are useful so far as they indicate affinities, and it is because I find such affinities in the plants before us, unrecognised by existing classifications, that I have suggested a new one. Whatever value different minds may attach to the fact, there exists

the great vegetative difference upon which I have dwelt between the Lycopodiacea and the Calamites on the one hand, and the Ferns on the other. There is certainly something more involved in this fact than "the old division of plants into trees and shrubs," with which Prof. Dyer compares it. Such a division is merely one of size and duration, not of organisation. Herbs, if they belong to the exogenous group, are as truly exogenous in their type as the most gigantic trees of the same class. Size has nothing to do with the matter. The same uniformity of type, apart from size, exists amongst my fossil cryptogams. True, the exogenous growth attains the fullest development amongst the large trees-but all the rudiments of this growth are equally to be found in the small ones, as my forthcoming memoirs will demonstrate.

The outer exogenous growth must be distinguished from the primitive vessels of the central medullary axis. I have yet to publish a remarkable series of facts illustrating this point. I have stated in a previous article that, in one sense, the exogenous vessels are a development of the vascular bundles of the living Lycopods. This is teleologically true rather than morphologically. Viewed in the latter aspect the two groups of vessels are independent of each other. The medullary vessels may be, and often are, primitive tissues formed at the first growth of the plant or of its young branches. The exogenous ones are something added, furnished by a cambium layer. The two groups retain their independent positions permanently, just as in living exogens the medullary sheath remains distinct from the woody cylinder which encloses it. W. C. WILLIAMSON

NOTES

We believe that the arrangements of the Eclipse Expedition are nearly all made, and that the numbers are now complete. The Expedition sails on Thursday next in the Mirzapore, arriving at Point de Galle on the 27th November, if all goes well. M. Janssen, we believe, is already en voyage. Prof. Respighi, of Rome, will accompany the English Expedition.

BOTH Mr. Hind and M. Stephan at Marseilles have obtained observations of Encke's comet. Mr. Hind thus writes: "It is a large, faint, and very diffused nebulosity-a different-looking object from what I remember it in one or two former returns, when it has been drawing just within reach of the telescope. The last observation on the 12th of October gives the following place:-At 9h 16m 185 mean time at Twickenham, right ascension, 1h 7m 37.8; north declination, 36° 47′ 38′′. The ephe meris for this appearance, published in Mélanges Mathématiques, of the Academy of Sciences of St. Petersburg, and calculated by Herr von Glasenapp, of the Russian National Observatory at Pulkowa, required, according to the above observation, correc tions of 36 seconds in right ascension and ten minutes in declination, subtractive in both elements. The comet's positions for the next few days will be nearly as follows:-

moon, and planets, made at the National Observatory, and news as to comets, minor planets, and the like. It promises to be very useful, and it is to be wished that other observatories will follow M. Delaunay's example.

THE contract for the new telescope which Congress has authorised the National Observatory at Washington to procure has been given to Mr. Alvan Clarke, of Boston, the well-known manufacturer of astronomical apparatus. It is to be of twenty-six inches aperture, and to be completed, according to contract, in about two years. It is understood that Mr. Clarke will again visit Europe for the purpose of carefully examining the principal telescopes there before completing the one in question. He has already minutely examined Mr. Newall's 25-inch, the chef d'œuvre of our English opticians, Messrs. Cooke and Sons, of York.

THE College of Physical Science at Newcastle-on-Tyne is now fairly at work. Already nearly fifty students are enrolled, and more are expected. Professors Aldis, Page, Herschel, and Marreco delivered their introductory lectures to large and appreciative audiences. Each of the professors, while touching especially on his own particular branch of science, dilated on the advantages accruing from the study of physical science, not only to the student who desires a special technical education, but to the community at large. Prof. Aldis, while expressing a hope that the advantages of the College would be thrown open to women as well as to men, made the following admirable remarks on the study of mathematics by women :“A mathematical training, by which I do not mean learning Euclid by heart, will be a good preparation for the study of political economy and for the study of nature; I think not a bad preparation for the proper management of a house, and the mother's duties towards her children. I am sure that the time spent in receiving such a training, even if by getting it a lad or a lass be obliged to commence active duties a year or two later, will be time well spent, and will give an impetus which will carry them both through life with an ease which scarcely anything

else will afford." We understand that Professors Herschel and Marreco intend that physical and physico chemical measurements shall be practised by the students, although there is yet no phy sical laboratory. At the time of going to press the question of admitting ladies had not been decided. A fair start seems to have been made, and we can only wish the new college as prosperous a future.

TRINITY College, Cambridge, has, it appears, the power of electing to its Fellowships men of scientific or literary distinction, and we are extremely glad to learn that Dr. Michael Foster has been thus elected. Dr. Foster was recently appointed to the newly-created post of Prælector in Physiology at the College, and this election to a further share of the emoluments and administration of the College proves that the members of the foundation are determined to carry out their intentions of promoting the study of Physiology in Cambridge. A temporary laboratory has been fitted up in the New Museums of the University, in which Dr. Foster gives lectures, and conducts the practical teaching. At the same time Mr. Hopkinson, Senior Wrangler of 1871, was elected a Fellow of Trinity College. These elections are the firstfruits of the act of last session admitting Nonconformists to a full share of the benefits of the University.

MR. WALTER WILLIAM FISHER, B. A., was on Saturday elected to an open Natural Science Fellowship at Corpus Christi College, Oxford, the examiners for which, Dr. Odling and Mr. A. Vernon Harcourt, made honourable mention of Mr. Christopher Childs, Scholar of Merton College. Mr. Fisher entered at Worcester College, from whence he gained a Natural Science Postmastership at Merton College, and was placed in the first class in the Natural Science Schools in Trinity Term 1870.

MR. MOSCARDI, from the Somersetshire College, Bath, has been

elected to a Mathematical Scholarship at Worcester College, Oxford, on the Finney Foundation, open pro hac vice; and Mr. White, from the Liverpool Institute, has been also elected an Exhibitioner.

It is gratifying to learn that Her Majesty has conferred the honour of Civil Companion of the Bath on Mr. J. H. Parker, the distinguished antiquarian. It is not often that we find either Science or Art so highly recognised in England; but is the Companionship of the Bath the fittest reward we have to bestow on scientific merit?

THE forty-fourth annual meeting of the Association of German Naturalists and Physicians has lately been held in Rostock. It has entered on the fiftieth year of its existence, having been founded in 1822 by Oken, who brought together twenty-one naturalists in Leipzig. Since that time a meeting has been held each year, with five exceptions. In 1831 and 1832 the meetings were suspended on account of the prevalence of cholera; in 1848, on account of political disturbances; and in 1867 and 1870 on account of war. The British Medical Journal states that the recent meeting was not so numerously attended as usual, many of the members having probably been detained at their homes through a fear of their professional services being required on account of the occurrence of cholera. One of the principal features of the meeting was an eloquent address by Prof. Virchow, on the position and prospects of natural science in the new national life of Germany.

SEVERAL friends of the Saturday half-holiday movement in London have offered the sum of thirty guineas for competition to London field-naturalists and microscopists for the encouragement of Saturday afternoon field excursions for botanical, geological, and microscopical purposes. The Duchess of Sutherland offers ten guineas to botanists in three prizes for the best collection of mosses, including the Hepatica, obtained within twenty miles of London; the Countess of Ducie ten guineas to

microscopists in three prizes for the best lists of the ponds and other aquatic resorts within fifteen miles of London, and the Microzoa found in them; and the Marquis of Westminster ten guineas to geologists in two prizes for the best list of open geological sections and exposures of the strata of the London district, giving the fossil species found in each section, and the characteristic species of each formation exposed, and for the best notes on the connection of the landscape scenery of the London district with its geology. This movement is an admirable one, and altogether to be commended. Professional collectors and dealers are wisely excluded from the competition, the prizes being intended exclusively for those with whom natural history pursuits are solely the recreation of their leisure after-business hours.

THE Athenæum states that Prof. Owen has written to the Mayor of Brighton, "on the subject of a survey of the Sussex Wealden deposits, the district made famous by the discoveries of Mantell." Any efforts made by Brighton to get together between the present date and August 1872, the date of the meeting of the British Association, a collection illustrative of the Iguanodon and other extinct animals, would be esteemed a favour, and would be appreciated by members and visitors. Prof. Owen recommends Mr. E. Charlesworth as peculiarly qualified for carrying out the scheme of the authorities, and benefiting permanently the Brighton Museum. After a recent meeting of the Town Reception Committee, Mr. Charlesworth addressed a few of the members of the Committee on the Weald deposits; but the town authorities have no power under existing Acts of Parliament to levy rates for paleontological researches.

THE Coventry Institute has arranged for a complete course of Science Classes in connection with the Department of Science and Art through the approaching winter, in inorganic chemistry,

animal physiology, magnetism and electricity, physical geography, and mathematics. We are particularly glad to see that they are arranged for young persons and adults of both sexes.

IN reference to the threatened destruction of what still remains of the Drui lical Temple at Avebury, a correspondent of the Times states that negotiations are in progress for the purchase of the land intended to have been sold for building allotments, so that the remains of this fine old temple shall remain in their present state.

PROF. PHILLIPS's so much looked-for work on the Geology of the Thames Valley is announced for publication. The Professor proposes to make it his text-book for a course of lectures on Oxford Geology, to be delivered this term at Oxford.

A SEVERE earthquake shock was felt at Callao and other places on the coast on August 21. The direction of the undulations was from N. W. to S. E, and the shocks lasted for fifteen seconds. Cero Azul and Pisco also suffered from the same shock.

ON Sunday the 8th of this month, a violent earthquake shock wis felt at Pera and Constantinople. The motion lasted for about five seconds. No great amount of damage was done.

THE terrible fire at Chicago, which raged during the early part of last week, and of which the ravages far exceed those of the Great Fire of London, affords us an additional example from which to judge of the truth of the so-much-disputed assertion, that extensive fires are almost invariably followed by heavy downpours of rain, which have been caused by them. In this case the latest telegrams assure us that the fire was chiefly checked on the third and fourth days by the heavy and continuous downpour of rain, which it is conjecture was partly due to the great atmospheric disturbances which such an extensive fire would cause, especially when we are told that the season

way to a European Museum. Five men were employed twentyfive days in felling this huge tree; its height is 302 ft., and its largest diameter 32 ft. The specimen was cut at a distance of 20 ft. from the base. The stump is covered in, and is now used as a ball-room! It has been ascertained from counting the annular rings that the tree is more than 2,500 years old.

A CORRESPONDENT of the Stationer announces a new fibrous plant for paper-making purposes, the Cineraria maritima, or sea rag-wort. Several very satisfactory results have been received from various paper-makers as to its great utility for trade pur peses, and there is every reason to believe, if proper attention is paid to its cultivation, it will in time become a staple article of commerce amongst manufacturers. The seed, at present, is im ported from France and the south of Europe, but preparations are being made for growing it on a large scale in this country. The same journal, in an article on "Iron-paper-making," gives a history of the manufacture of the thinnest sheet of iron ever rolled, manufactured by Messrs. W. Hallam and Co., of the Upper Forest Tin Works, near Swansea. The sheet in question is Ioin. by 5in., or 55in. in surface, and weighs but 20 grains, which being brought to the standard of Sin. by 5in., or 44 surface inches, is but 16 grains, or 30 per cent. less than any previous effort, and requires at least 4,800 to make rin. in thick

ness.

Ir is stated that tobacco in any form may be used with great advantage against snakes of all kinds. By pouring a decoction of it in suspected places, they are driven away, and this fact is known to both the natives of Hindostan and to those of North and South America. If it can be administered to them it is certain death.

IN his "Contributions towards the Materia Medica and Natural History of China," Mr. Frederick P. Smith records the following facts respecting the use of Fungi as food in the Celestial

dry.

THE Association formed in California for the purpose of introducing Eastern fish into the waters of that State has received a first instalment in 15,000 young shad, hatched in the Hudson River just a week before, and brought in large tin cans filled to the shoulder with fresh water. They proved to be in excellent condition on their arrival on the Sacramento, and were taken thence higher up the river to Tehama, where it was proposed to plant them. The expenses of this enterprise are borne from an appropriation on the part of the State of 5,000 dollars for this special purpose.

A VERY remarkable collection of medicinal and other drugs has been brought together in the Exhibition of Natural Industry of the United States of Columbia or New Granada in the City of Bogoti. Among febrifuges it includes the yellow quina of Zaragozi and the Sarpolata, which is considered more effective even than quina of dye plants. It is observed that Mr. P. M. Gonsalez has produced three shades of green from plants discovered by him in Antioquia. The Achivilla of that province produces golden yellow, the Bruj1 a splendid red, the Ojo Venado an intense black, and the plant of the Sagus a blue equal to indigo.

THERE is in the Museum at Cassel a curious collection illustrating European and other trees. It is in the form of a library, in which the back of each volume is furnished by the bark of some particular tree, the sides are made of perfect wood, the top of young wood, and the bottom of old. When opened the book is found to be a box, containing either wax models or actual specimens of the flower, fruit, and leaves of the tree.

THE New York Times states that a solid section cut from one of the original "big trees" of California is in New York on its

of every province under the name of Hiang-kw'an, and have some medicinal or dietetic properties assigned to them. The Polypori, or Boleti, are generally preferred to the Agarics, so largely eaten in Europe. Kwei-k'ai, or Ti-k'ai, are edible Agarics, or Helvella, and perhaps include poisonous sorts. They are burnt and applied to swellings and sores. Ti-rh is probably an Agaric, said to be tonic in its effects. The Muh-rh are a numerous class of parasitic fungi growing on trees. They are much eaten. They come from Ching-ting fu in Pehchihli, Shun-king fu and Sui-ting fu in Szch'uen, Li-pʻing fu in Kweichau, Yun-yang fa in Hupeh, and from Shang chau and supply a portion of this food. The Shih-rh is a Polyporus Han-chung fu in Shen si. Manchuria and the Amur country brought from Fung-t'ien fu in Shingking, Hwui-chau fu in Nganhwui, Nan-kang fu in Kiang-si, and from Lai chau in Hunan. Tu ko'an, or Ti-tan, are Agarics or Amanitas, or answer to the "toad-stools" and other injurious fungi. Some of them are said to cause irrepressible laughter. Alum and chicory are reported to be antidotal to their poison. Japanese mushrooms appear in the tariff as Tung yang-hiang-ku.

MUCH interest was excited in the scientific journals some time ago by the accounts given in the Panama papers of the flights of a beautiful butterfly, the Urania leilus. By late advices from Panama we learn that these insects were passing over that city, from west to east, in July last, in very large numbers, and in some cases were attracted into houses by the light so as to almost fill the apartments. They are said to be accompanied during the day by swallows and swifts, and in the night by the different species of goat-sucker, which probably destroy large numbers. Nothing is at present known, however, of the place whence they cane, nor the region to which they are ultimately bound.