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pass around the clog in the spirals by way of the unfilled pitted vessels and to enter the spirals once more farther up. Were this not so, i. e., were pitted vessels filled as readily, as quickly, and as fully as the spirals, we should have not the gradual wilt of leaf after leaf up and down the stem, but the sudden collapse of all the leaves beyond the original point of attack. This is exactly what does happen in watermelon vines attacked by Fusarium niveum, (for a brief account of this parasite see Proc. Am. Asso. Adv. Sci., Vol. 43, 1894, p. 289, and Ibid, Vol. 44, 1895, p. ) where the pitted vessels appear to fill with the fungus as soon, if not sooner, than the spirals. These two diseases of cucurbits are very interesting from a physiological standpoint, and both parasites lend themselves readily to infection experiments, their slightly different behavior being, perhaps, accounted for by the fact that the fungus is strictly ærobic, while the bacillus is facultative anaerobic. Whatever be thought of butter or gelatine, it certainly cannot be maintained that the mere presence of these parasites in the lumina of the vessels destroys the carrying capacity of the uninjured walls, and yet they act quite as effectually as gelatine, paraffin, or cocoa butter plugs, causing, when they fill the vessels only incompletely, a flabbiness of the foliage, which is proportionate to the extent of the plugging and to the activity of the transpiration, and which may give place to complete turgor in periods when the transpiration is small (night, early morning, or damp days), and producing, when they completely fill the lumina of the vessels, an entire collapse of the foliage, from which there is no recovery. In case of the cucumber this collapse takes place as soon as the spiral vessels leading into any petiole are filled by the bacillus.

EDITOR'S TABLE.

-PROFESSORS in the scientific departments of our schools should exercise their influence to prevent the spoliation of nature that is going on at so rapid a rate in our country. We do not especially refer at present to forest fires which involve so much financial loss that our state and general governments are moving in the direction of their prevention. In passing, however, we must refer to the railroad companies as delinquents in this matter, and insist that heavy fines be imposed on them in all cases where fires can be shown to have originated from locomotives. We counted from the car windows of a train not long since, twelve distinct fires burning near the track in the space of a few miles, in a forest covered region not far from Philadelphia, and no one appeared to pay any attention to them.

We wish, however, to refer to the destruction wrought near our cities by the uprooting of plants and the breaking off of branches for purposes of decoration of public and private houses. Within reasonable bounds the vegetable world furnishes material for such decoration, but the practice is carried beyond the rich resources of nature to meet. Our woods are being rapidly stripped of ornamental plants for miles all round our large cities. In many regions the Epigaa repens is completely destroyed, and the blooms of the dogwood and kalmia no longer appear. Lycopodia are uprooted over large tracts, and must now be brought from considerable distances. Some of the ruin is wrought for church decoration, and the girl-graduate is responsible for more of it. Teachers of the natural sciences can teach their hearers that this cannot go on forever. Especially can they point out that botanical classes should not gather arm-loads of orchids of fastidious habits if they do not wish to see the localities destroyed or the species well nigh exterminated.

The authorities in charge of our public parks might, in some places, profitably change their point of view. A park should not consist principally of graded paths lined with stone curbs or walls, separated by tracts of close shorn grass. Shrubberies of nature's planting should remain, and the vines with which nature festoons the forest should not be cut down. No harm is done if there are places where rabbits may hide, and wild birds may nest. Even an owl or two might be permitted to keep down so far as he or she can, the English Sparrow nui

sance.

In fact, a park is not necessarily a place from which nature is

excluded. The perpetual clearing of undergrowth means also the ultimate destruction of forest, as the natural succession is thus prevented.

As an offset to this public and private vandalism, we have near our cities a goodly number of citizens who preserve more or less of nature in their private parks. It will be to these to whom we must look to replenish our stock of native shrubs and herbs, if the vandal continues to have full swing elsewhere.

THE forty-fifth meeting of the American Association for the Advancement of Science to commence at Buffalo, N. Y., on August 22d, will be characterized by one feature which is deemed by the society an improvement over previous meetings. No excursions will be made during the working hours of the day during the session, only those occupying evening hours being acceptable. At the close of the meeting the field for such diversions will be clear. The geological excursions have been so arranged as not to conflict with the meetings; and the six scientific societies, which meet about the same time, it is hoped will contribute to the importance of the general gathering. It is anticipated that these arrangements will arrest the tendency to dissipation of energy which has been apparent during the last few years. If the habit of many of the embryologists to absent themselves could be overcome, the full force of the Association would be represented. It is expected that a number of evening lectures will present to the public the latest results of research in America.

RECENT LITERATURE.

Surface Colors :-The object of the little book on this subject' by Dr. Walter, of Hamburg is apparently to furnish zoologists, mineralogists, and chemists with an accurate explanation of certain color phenomena which are not as yet universally understood, and which are incompletely treated even in the best text-books on Physics. The keynote of the whole book is given in a single sentence of the introductory chapter. The intensity of the light reflected from any body may be calculated by Fresnel's ordinary formulæ for colorless substances, in the case of those rays which are slightly or not at all absorbed by the

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1 Die Oberflächen-oder Schillerfarben, von Dr. B. Walter, pp. VIII + 122, Braunschweig, F. Vieweg und Sohn, 1895.

body in question; but for wave-lengths which are strongly absorbed by the given substance, Cauchy's formula for the intensity of metallic reflection should be used." It appears from these formula that the intensity of the reflected light depends on the index of refraction and on the coëfficient of absorption of the substance presenting the reflecting surface. Since both these factors are different for light of different colors, it is shown that white light must be reflected with some of its "components" relatively weaker than others, i. e., no longer in the proper proportion to give the sensation of white light. The application to the colors seen in the mineral kingdom is illustrated by the example of magnesium cyanplatinite, Mg Pt (CN),, where, as is true of most crystals, the index of refraction and the coefficient of absorption vary with the direction in which the light vibrates, as well as with the wavelength of the light. The extent to which true surface color is observable on minerals is not indicated, though the possibility of a very wide application is clearly shown.

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In the appendices, certain mathematical aspects of the subject are treated in a manner suited to the requirements of physicists.-A. C. G.

The Whence and Whither of Man.'-This book comprises a series of lectures dilivered at Union Theological Seminary, with some additional matter. The author discusses the doctrine of Evolution from the standpoint of a theologian. He endeavors to show that the great law of animal and human development as revealed in the sequence of physical and mental development is that those species survive which are best conformed to their environment; that this law holds good in the development of the rational, the dominant faculty in man; and finally, to become higher man he must develop a moral-nature by attaining a knowledge of himself as a moral agent, and while not disregarding the body, he must subordinate its appetites to the higher motives furnished by right and duty. It is in following this line of thought that the author hopes for a definite answer as to the future destiny of man.

The closing chapter deals with the present aspects of the theory of evolution. He here compares the various hypotheses of evolution and considers their merits. He judiciously selects the good elements of all of them, concluding that "each theory contains important truth." He concludes that Nägeli's view of " initial tendencies" is too often undervalued. "My own conviction is steadily strengthening that without

The Whence and Whither of Man. By John M. Tyler, New York, 1896, Charles Scribner's Sons, Publishers.

some such original tendency or aim, evolution would never have reached it present culmination in man." He quotes Boveri that "there is too much intelligence in nature for any purely mechanical theory to be possible." It is curious that these authors do not perceive that the sensation of protoplasm, (consciousness), furnishes the basis for the exhibition of the intelligence which they observe, and which has itself undergone evolution coincidentally with the organism. Both orthodox and heterodox evolutionists (theologically speaking) seem equally slow to adopt this view.

Prof. Tyler's book is eminently moderate and reasonable, and will introduce evolution to a large class of readers in an agreeable form.

Cope on the Factors of Organic Evolution.-This book is divided into three parts: I, The nature of variation; II, The causes of variation; III, The inheritance of variation. In the first part it is endeavored to show that variation is not promiscuous or multifarious, but pursues direct courses towards definite ends. This is done by presenting the variations of existing species as to color and structure, and by an examination of the series presented by the forms of vertebrate life in past geologic ages. The latter presentation is a general phylogeny of the vertebrata, with special sections on that of the horse and that of man. The second part is divided into chapters which deal with the physical energies as causes of variation, and the effects of molar motion as seen in variation. These methods of evolution are termed respectively physiogenesis and kinetogenesis. Especial attention is given to kinetogenesis in connection with the phylogeny of vertebrates, since it is in these two fields that most of the original work of the author has been done. The author has demonstrated that the primary cause which has moulded the vertebrate skeleton is molar motion. In the third part, the inheritance of the characters so produced is shown to be the rule, thus demonstrating the inheritance of acquired characters. Theories of inheritance are discussed, and that one which asserts the transmission of energies to the germ plasma is defended. These energies are believed to be the results of a composi tion between inherited and acquired energies, the whole of them being referred to a class distinct from the inorganic energies, which he has named Bathmic. The last chapter in this part is devoted to a consideration of the relation of consciousness to movements, and hence as a cause

3 The Primary Factors of Organic Evolution, by E. D. Cope, Professor of Zoology and Comparative Anatomy in the University of Pennsylvania. Chicago: Open Court Pub. Co., Feb., 1896, $2.00.

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