separated in regard to animal distribution. This latter point goes far toward being the sole cause of regions. Any large mass of land separated from the rest of the world will, in the course of time, become inhabited by a peculiar set of animals, and obtain a comparative balance or stability of life. Thus a number of species are evolved which forms a sort of compound whole, the life of a region. So a region may be defined as the area occupied by a peculiar grouping of animals which are isolated from the life of the rest of the world; the word 'peculiar' referring to the animals as a whole, and the isolation as of a limited and not absolute degree.

At

Accepting the above definition, the world can be conceived of as divided into regions, which, if the land and sea remained at rest, would be permanent, but constantly growing more and more distinct. But the land is not permanent. While the main mass is a fixture, minor changes occur, which join and separate the continents. As soon as two lands are joined, unless some other very powerful barrier exists, the life of the two at once begins to blend. The more potent kinds survive, while the weaker die out. The first, together with the life modified by the new conditions (new species evolved), in the course of time form a single region. On the other hand, if a land become divided into two, the reverse takes place, and two regions are formed. To me the palearctic and nearctic regions seem to offer illustrations of both these processes; the connection for life having been made and broken between the old and new worlds, probably by means of Asia, more than once. present it is broken; and the nearctic and palearctic regions are formed or forming from a previous circumpolar region. With the tentative definition given here, the two are regions, since they do not form a group, and are separated. No lack of percentage differences can make the life of the two regions closely related: a change in one does not necessitate a change in the other. This also answers the circumpolar question: the resemblance in zones is due, first, to the imperfect obliteration of the old circumpolar region; and, secondly, to the fact that some of the forms which inhabited it have been driven down into the southward-pointing peninsulas, where the conditions of their life are easier. According to this definition, Madagascar should be regarded as the remains of a fading region, rather than a part of the Ethiopian. The resemblance between Africa and India is due to a southward migration which occurred not so long ago, very likely on account of the ice age, from a northern central point.

The above crude suggestions would seem sufficient to show that regions are more than numerical relations, and have an evolution of their own. J. AMORY JEFFRIES.

Panther Creek coal-basin.

I have just read your review of the Panther Creek atlas, in SCIENCE, No. 11, and my attention has been directed to what I consider a very just and proper criticism of two special features of the atlas sheets: 1°. The discordant scales of the mine (800=1'') and topographical (1600′ = 1") sheets. 20. The use of the magnetic instead of the true meridian. As a geological critic, I should be disposed to boldly condemn what you have referred to as merely misfortunes. After an association of nine years with Professor Lesley on the Pennsylvania state survey, I am convinced, that, in the successful conduct of such a survey, it is quite impracticable to attempt to attain a purely technical and systematic standard of work. All that can be lone is to approach as near as possible to such a

standard, while meeting the practical demands for geological results, to aid in the economical exploitation of our mineral resources. This latter is what has popularized the work of the Pennsylvania survey, and accounts for its uninterrupted continuance with liberal appropriations for a state survey, since 1874.

The published results of the survey so far relate mostly to topographical, geotectonic, and stratigraphical geology in their economical bearings, with the exception of two volumes on paleobotany. Had any other plan than that of Professor Lesley's, which he has so efficiently carried out, been instituted, the survey would never have been so liberally supported by our state legislature, and probably would have been discontinued several years ago. The important thing in a state survey is to do the best we can. If we attempt too much, we fail in all.

In regard to the discordant scales and magnetic meridian, I would say: 1°. That the publication committee of the board of commissioners has never before authorized the printing of general maps on a scale larger than 1600=1". This scale was found quite too small for the anthracite-mine sheets, and it was only after the most careful consideration on the part of the committee that a scale of 800=1′′ was adopted for the mine sheets. The smaller scale was unfortunately adhered to for the topographical sheets, on account of the cost of publication. 2°. In the Panther Creek basin, the magnetic meridian of 1869 is always used in all surveys; and the block-lines referred to this meridian on the atlas sheets have been similarly placed on all the large working mine maps. In this form the sheets are of much greater practical value for ready reference. Had the publication of this atlas been delayed until the completion of the astronomical determinations of the survey in this locality, we should probably not have obtained an additional appropriation to continue the survey, which we now feel assured of receiving.

Philadelphia, April 21, 1883.

CHARLES A. ASHBURNER, Geologist in charge.

Crayfish.

In August, 1882, while in Fairmount Park, Philadelphia, I found a crayfish in a brook emptying into the Wissahickon Creek. It had its under parts covered with young crayfish about one-eighth of an inch long.

Professor Huxley says that the English species, Astacus fluviatilis, lays eggs in May and June, and the young leave the female in a few days; but the young staid ten days with the female after I found them. There seems to be a difference in their habits in this respect. Last Friday, April 6, I found a female crayfish with young ones clinging to it, which I caught; and a friend now has it in a tank. Do crayfish lay eggs both early in the spring and late in the summer? RICHARD M. ABBOTT.

Trenton, N.J.
[The writer of the above is eleven years of age.
ED.]

Marking geodetic stations.

The writer of the article in SCIENCE of April 13, 1883, p. 269, in referring to the method of marking the geodetic stations in the N. Y. state survey, makes the statement that the U. S. coast survey stations are indicated by no surface-mark whatever,' trusting entirely to the underground-mark for the preservation of the station. The writer has, doubtless, been misled by visiting a station from which the surfacemarks have been removed by curious or malicious persons. In the coast survey the greatest stress is

laid upon the importance of carefully marking stations; and the detailed instructions in regard to the subject occupy two quarto pages in the manual ‘On the field-work of triangulation,' issued by the survey. The most common method used is the one which has been copied by the N. Y. state survey. Other methods, however, are used in special cases. For recovering a station, the main dependence is upon the surface-marks, and the underground-marks are used only for protection in case of the destruction of the others by accident or design. H. W. BLAIR,

Washington, D. C., April 22, 1883.

Assistant Coast and geodetic survey.

Freezing of liquids in living vegetable tissue.

The conclusions of Mr. Meehan in relation to the above topic (SCIENCE, p. 229) seem to me scarcely warranted by the best authenticated facts in vegetable physiology. Experimental investigations and researches, undertaken many years ago, led me to the following deductions:1

1. That the sap of many living plants can be frozen by the application of a degree of cold not much below that required to freeze it when removed from the plant; and that in very cold climates the sap of all perennial plants must be frozen in all parts during the winter months.

2. That the congelation of the juices of living vegetables does not, as many phytologists have imagined, necessarily and inevitably result in the death of the whole plant, or of the part in which it takes place, but, on the contrary, that frequently no injurious consequences follow. Consequently it is unwarrantable to assume that a plant which is not killed by severe cold never was frozen; and therefore it is unnecessary to invoke the aid of a vital power' to enable plants to survive the influence of cold sufficiently intense to freeze their juices when removed from the living plant.

3. That the bursting of the trunks of trees in high latitudes is not due to the expansion which the sap undergoes in process of congelation, but to the unequal contraction which takes place in the trunk (usually after the complete congelation of its juices) in consequence of a sudden depression of temperature. In short, that the rupture of the trunk in such cases is due to the same cause as the rents in the frozen ground, and the cracks in large sheets of thick ice, which occur in high latitudes when there is sudden accession of cold. This view is fortified by the fact that the coefficient of contraction (or expansion) of ice is greater than that of any other solid body hitherto examined, with the exception of hardened caoutchouc, or ebonite. JOHN LECONTE.

Berkeley, Cal., April 17, 1883.

Sun's radiation and geological climate. In his review of Whitney's climatic changes, Mr. Gilbert says, "His [Whitney's] hypothesis that the intensity of solar radiation is gradually lessening, by reason of the dissipation of solar energy, . . . will be admitted by most students." Mr. Whitney and his reviewer fall into the very natural error, that a loss of heat, and, of course, of energy, is necessarily accompanied by a fall in temperature. Paradoxical as it may appear, a loss of both heat and energy may

1 For the exposition of the basis of these deductions, the reader is referred to the memoir of the writer, entitled "Observations on the freezing of vegetables, and on the causes which enable some plants to endure the action of extreme cold." — (Proc. Amer. assoc. adv. sc., vi. 338-359; Amer. journ. sc. [2], xiii. 8492, 195–206.)

produce a rise in the temperature of the body that loses them. If it be true that the sun is, as is now thought by many eminent scientists, a globe of gaseous matter, then, under the long process of giving off heat, it has actually been growing hotter, and the intensity of its heat on the earth's surface to-day is greater than it was in the early geological epochs.

The world is indebted for this curious fact to Mr. J. Homer Lane.1 I quote from Newcomb's Astronomy, p. 508: "The principle in question may be readily shown in the following way: if a globular, gaseous mass is condensed to one-half its primitive diameter, the central attraction upon any part of its mass will be increased fourfold, while the surface upon which this attraction is exercised will be reduced to one-fourth. Hence the pressure per unit of surface will be increased sixteen times, while the density will be increased only eight times. Hence, if the elastic and gravitating forces were in equilibrium in the primitive condition of the mass, its temperature must be doubled in order that they may still be in equilibrium after the diameter is reduced one-half."

Admitting, then, the gaseous condition of the sun, as, under our present knowledge, we seem compelled to do, we must also admit that the intensity of the sun's radiation of heat has been slowly increasing through the ages, and to-day is greater than at any previous time. The increase may have been small; but, so far as there has been any change, it has been in the direction of an increase, and hence cannot explain the undoubted decrease in the general temperature of the earth's atmosphere indicated by the paleontological record. C. B. WARRING.

Distribution of public documents. Few outside of the ranks of professional politicians will disagree with the report of the committee of Congress on the printing and distribution of public documents, or with the tenor of the editorial remarks on the subject in No. 9 of SCIENCE. But it is to be feared that it will be as difficult to induce the average congressman to dispense with these lubricants of the political machine as with the senseless distribution, through the department of agriculture, of seeds that can as well be bought at any country store. If any means can be devised by which the 'costly and beautifully illustrated volumes' shall reach those for whose information they were written, instead of serving to adorn the nurseries of influential ward strikers and campaign committee men, it will redound greatly to the benefit of scientific knowledge and progress; for at present it is mainly through the medium of second-hand book-stands that those interested can occasionally get the professional works of which their political insignificance did not render them worthy recipients.

There is one notable exception, however, to this extravagance and misdirection of precious documents, the result of one of those spasms of virtue mentioned in the editorial. I refer to the law concerning the distribution of the publications of the geological survey, to which director Powell has called attention in a circular issued some time ago. According to the terms of this law, these documents, excepting the general report, can be obtained only by purchase or exchange; that is, the scientific workers of the country may at first get what may be deemed the equivalent of their own publications, or, possibly, of rare works in their possession. But when this resource is exhausted, the only method open to them, for obtaining what in many cases is the sequel of 1 See Amer. journ. sc., July, 1870.

their own work in the states, is to purchase the memoirs out of their abundant professorial incomes. What that means when it comes to the illustrated memoirs and atlases, most needed by the actual worker, is too obvious to need discussion. They will simply have to be done without by those not within reach of a large public library.

Heretofore, a certain number of copies of such publications, outside of those placed at the disposal of congressmen, were distributed gratuitously to those known to be actively interested in the subject, by the authors, or heads of surveys, who knew exactly whom to reach among their scientific co-workers; and the stimulus thus given to research and scientific intercourse was very great. All this is now effectually embargoed: the very men whom these documents should reach are cut off from them by this penny-wise and pound-foolish legislation.

If it be true that the United States cannot afford to continue the expenditure involved in the gratuitous distribution of such costly publications, even for the encouragement of scientific research, it would be far better that their cost should be reduced from the magnificent quartos and royal folio atlases to such material and dimensions as can be afforded consistently with a judicious gratuitous distribution, intrusted, for example, to the judgment and discretion of the director, the Smithsonian institution, and the National academy, severally or jointly. The scientific publications would then be quite sure not to be wasted, and yet would with equal certainty reach those whose active interest in the progress of science should entitle them to their possession. This is the more needful, since the extension of the national survey into the states will, for the time being, undoubtedly render state surveys less numerous, and more scantily endowed for scientific work; so that the publications of the national survey will be the chief source of information hereafter. It does seem that what the states could afford to do gratuitously for their own citizens could be afforded by the national government, now that this kind of work has practically passed into its hands.

Berkeley, Cal., April 19, 1883.

THE AGRICULTURAL

E. W. HILgard.

EXPERIMENT

STATION OF CONNECTICUT.

Annual report of the Connecticut agricultural experiment-station for 1882. New Haven, State, 1883. 114 p. 8°.

THE major portion of this report is, as usual, occupied with analyses and valuations of commercial fertilizers, and divers other fertilizing materials, and though valuable in its way, and in accordance with the design of the station, contains little of general scientific interest. The review of the fertilizer-market for the past year, on pp. 56-60, must prove of considerable aid in the valuation of fertilizers, and will doubtless attract the attention of both manufacturers and consumers.

Among the fodder analyses are two of duplicate samples of field-corn and of fodder-corn, selected with especial care, and also of ensilage from the same material. These analyses dis

closed the interesting fact, that the duplicate samples of the same material differed more in some cases than did the ensilage and the fresh substance. These results illustrate the great difficulties that stand in the way of preparing a fair sample of such a bulky plant as maize, and throw considerable doubt on the accuracy of some of the recently published results regarding the changes which maize undergoes in

the silo.

The most generally interesting portion of the report is the paper on, Milk,' by Dr. E. H. Jenkins, which includes the results of several analyses of the milk of single Guernsey cows, and of over two hundred partial analyses of the mixed milk of herds. These results afford valuable data in regard to the variations which may occur in commercial milk, and the possibility of establishing by law a standard of purity for milk. In regard to the variations in the milk-solids, "an inspection of all the results... leads to the conclusion, that, in pure herd-milk, the solids may in some cases, and at certain seasons, sink as low as 10 or 10.5 per cent, and the fat to 2.6 per cent; and that very frequently (in 28 per cent of the samples examined at this station) the solids are less than 12 per cent."

In one case the total solids amounted to only 9.79 per cent, though it was not certain that the milk was unadulterated, and, in six cases out of two hundred and seven, to less than 10.5 per cent. Dr. Jenkins comes to the following conclusions regarding the standard of purity for milk:

As evidence of watering, simply, specific gravity furnishes by far the most satisfactory test; and, if 1.029 is adopted as a minimum, no pure milk will be condemned. In some cases moderately watered milk may escape

detection.

"If we will establish a minimum limit for the percentage of solids and fat which shall in no case condemn pure milk in any locality, we shall have to make it absurdly low, and thus offer a premium on watering milk of good quality."

While evidently doubting the practicability of establishing a general standard of purity for milk, Dr. Jenkins thinks it possible to establish by mutual consent local standards for limited districts, where the pasturage and other conditions are tolerably uniform. Where this is done he would not have the question of the purity of the milk raised at all, but would simply condemn all which falls below the standard as too poor to use. Both suggestions seem worthy of general consideration.

FOSSIL BOTANY.

Cours de botanique fossile fait au Muséum d'histoire naturelle. Par M. B. RENAULT. 2ème année. Paris, Masson, 1881. 194 p., 24 pl. 8°.

In the first volume of this remarkable work, which was reviewed in this country a year since (Proc. Amer. phil. soc.), the author has exclusively considered the Diploxyleae, and given the history of each of the families of that class, the Cycadeae, Zamiae, Cycadoxyleae, Cordaiteae, Paroxyleae, and Sigillariae. As the question of the relation of the Paroxyleae and Sigillariae is of the greatest importance for the history of the evolution of plants, it has been considered again in this year's course, though, in the preceding, the structure of the Sigillariae had been already examined. The author therefore proposes to study the most highly organized vascular cryptogams, and to search by studying the anatomy of the stems, the branches, and the roots, if, as has been asserted, any of them, at a certain point of their existence, take on the phenogamic character so distinctly that a separation of these two great divisions becomes impossible.

The essential characters of the vascular cryptogams to be examined are presented in a table. They are divisible into two prominent groups: 1°. The Lycopodiaceae and the Rhizocarpeae, which are heterospores, though some Lycopodiaceae are both heterospores and isospores; 2°. The Ophioglosseae, the Equisetaceae, and the ferns, which are isospores.

The first group of the Lycopodiaceae is that of the Lepidodendreae, beginning in the first chapter with the genera Psilophiton and Lepidodendron. Chapter 2 examines in detail the anatomical structure of three types of Lepidodendron; viz., L. Rhodumnense, L. Harcourti, and L. Justieri. Chapter 3 relates to the anatomy of the fructification of Lepidodendron or to the Lepidostrobi. Chapter 4 gives a brief examination of the characters of the other genera referred to the Lycopodiaceae. Chapter 5 compares the distinctive characters of Sigillaria and Lepidodendron, the differences, after discussion, being set forth in a comparative table; the Sigillariae being recognized as related to the phenogamous plants, and the Lepidodendreae to the Lycopodiaceae.

To the Rhizocarpeae belong, at the present epoch, the genera Pilularia, Marsilia, Salvinia, and Azolla. Of these, no remains have been found in the carboniferous; but species of the genera Sagenaria and Sphenophyllum seem to be related to this family. The history of the genus Sphenophyllum, as heretofore known,

and the description of the species, are given in chapter 6. The anatomical structure of Sphenophyllum is discussed in chapter 7; the woody axis is always full, not hollow, and inflated at the articulations only when a branch is formed; the stems, the leaves, the bark, the roots, the fructification, are treated.

With chapter 8 begins the treatment of the cryptogamous isospores, which may be summarized as follows: Equisetaceae. The living plants of this family have only one kind of spores; examination of the stems and other organs. Asterophyllites. Tiges, branches, and principal species described; two forms of fructification described (Wolkmannia and Macrostachya). Chapter 9. Annulariae. - Description of the different organs; stems, branches, and fructification; and of the species. Chapter 10. Fructification of Annularia, considered with species of uncertain relation (Bruckmannia and Cingularia). This chapter ends with a comparative table exposing the characters of the Asterophylliteae and the Annulariae. Chapter 11 contains descriptions of the genera Schizoneura, Phyllotheca, and Equisetum. Nine species of Schizoneura and twenty of Equisetum are described, none from the paleozoic formations. The genus Calamites and its different organs are described in chapter 12.

The concluding chapter contains a table showing the different formations where the plants described in the volume have been obtained. The true Equisetaceae do not appear lower than the trias. The range of Asterophyllites, Annularia, Calamites, and the Lycopodiaceae, is from the upper Permian to the culm or subcarboniferous measures; that of Psilophitum is in the Devonian and upper Silurian. The volume ends with considerations on the distribution of the plants, on the climate as indicated by their nature, and on certain organs which may be useful in classifications. It would be useless to eulogize this excellent work, which is illustrated with twentythree splendid plates. The above summary sufficiently shows its importance.

A NEW CALCULATION OF THE ATOMIC

WEIGHTS.

Die atomgewichte der elemente, aus den originalzahlen neu berechnet. Von Dr. LOTHAR MEYER und Dr. KARL SEUBERT. Leipzig, 1883, Breitkopf & Härtel. 246 p. 8°.

THE great importance to chemistry of an exact knowledge of the atomic weights is well illustrated by the recent activity of chemists in

that line of investigation. About two years ago, Prof. G. F. Becker published his 'Digest'; a year later my own Recalculation' appeared; and now comes a third volume on the subject by Professor Lothar Meyer and Dr. Karl Seubert of Tübingen.

A comparison of this new work with the other two shows, that, in general terms, it is intermediate between them in its character. Becker collected the data relative to atomic weights, and brought them into systematic shape, but attempted no thorough recalculation. Meyer and Seubert classify and recalculate the published weighings, and make many valuable reductions of apparent weights to absolute or vacuum standards; but, with a few exceptions, they do not attempt to combine the work of different investigators, and they reject the method of least squares as inapplicable to the data at hand. My own effort was to reduce determinations as far as possible to common standards, to combine all similar data into general means, and to compute from all the evidence the most probable values for the atomic weights of the different elements. In so doing, I applied the method of least squares, and I see as yet no reason for discrediting that manner of discussion. Each of the three volumes fills a definite place; and, in any future revision of the field, each will be found a useful supplement to the others.

In general, the results obtained by Meyer and Seubert differ but slightly from mine. In comparing the atomic weights of sixty-six elements, the difference between the two recalculations falls within a tenth of a unit in thirtyseven cases, and is greater than a tenth in twenty-nine; but among the latter are found most of the rarer and less perfectly known metals. In many instances the differences are due to a trifling fundamental difference in the value assigned to oxygen. The MeyerSeubert value is 0=15.96; mine is O=15.9633 : and this slight variation in the third and fourth decimal places sometimes is multiplied among the higher atomic weights to an appreciable amount. Where the two recalculations agree, they serve to confirm each other: where they differ, they indicate the important fields for further investigation. Most of the differences, however, are mainly due to differences in the manner of computation.

In some respects the new recalculation is open to criticism. Inasmuch as Meyer and Seubert rarely attempt to combine the available data, they are, perforce, compelled, in dealing with each element, to select more or less arbitrarily the results of one investigation, and give

it preference over all the others. This they do without assigning reasons for their choice; and such a lack of critical statement is much to be regretted. Again: the arrangement of the material is inconvenient, notwithstanding the fact that there is a well-classified index, both for elements and for authors. For example: aluminum, instead of being discussed in a division by itself, is treated in separate ratios on pp. 22, 23, 83, 139, 151, and 193; and a comparison of the results of different investigations is thus rendered a very trouble

some matter.

Some omissions are noteworthy, and seem difficult to explain. Such, for example, are Cleve's determination of the atomic weight of scandium, Julius Thomsen's synthesis of water, and Russell's hydrogen series for cobalt and nickel. Russell's work on the oxides of these metals is given, and his results receive final acceptance; but wherein they are preferable to those of Lee is not stated. Another curious set of omissions occurs under antimony. Here are cited Professor Cooke's latest bromide series, and his set of results comparing the trisulphide with the chloride. But his syntheses of sulphide from the metal, and his valuable iodide series, are altogether ignored, while his earlier bromide series barely receives mention. Finally, nothing is said concerning Dumas' investigations upon the occlusion of oxygen by silver, although no recalculation of the atomic weights can safely ignore so important a factor. F. W. CLARKE.

WILDER AND GAGE'S INTRODUCTION TO ANATOMY.

Anatomical technology as applied to the domestic cat: an introduction to human, veterinary, and comparative anatomy. By BURT G. WILDER, B.S., M.D., and SIMON H. GAGE, B.S. New York and Chicago, A. S. Barnes & Co., 1882. 25+575 p. 1. 8°.

THIS book the authors state to have grown out of their needs as instructors of students preparing for practical work in human, veterinary, or comparative anatomy. To students of the first and second of the above classes there is no doubt it will prove extremely useful. It is probably correct to say, that, although containing a good deal of irrelevant matter, and blemished by the unnecessarily extensive employment of a novel terminology, it contains by far the best set of directions for the dissection of a mammal below man in the scale, ever published for the use of that large class who prefer or are compelled to enter,