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will too probably endure till we have critical insight. But there is room for ceased to be personally interested. poets as well as for arithmeticians; and

I cannot, indeed, get it out of my Arnold, as at once poet and critic, has head that we slow-footed and prosaic the special gift—if I may trust my own persons sometimes make our ground experience of making one feel silly surer ; and that, for example, poor and tasteless when one has uttered a Bishop Colenso, whom Arnold ridi- narrow-minded, crude, or ungenerous culed as the typical Philistine critic, sentiment; and I dip into his writings did some good service with his prosaic to receive a shock, unpleasant at times, arithmetic. There are cases in which but excellent in its effects as an intelthe four rules are better than the finest lectual tonic.— National Review.



That agencies in themselves seem time a chemical laboratory, in which ingly insignificant are capable, when acids and other substances secreted by operating continuously during long the organism are made to act upon the periods of time, of effecting stupendous finely pulverized materials of the soil. results is a well-worn theme of the geol The investigations which during the ogist. Mr. Darwin has familiarized the last thirty or forty years have been carreading public with what must be re ried on with a view to determining the garded as one of the most striking and, nature of the ocean-floor, and of the at first sight, paradoxical illustrations operations that are going on there, have of this principle as applied to the land made us familiar with some illustrations areas of the globe. In his latest pub- of the same principle, that are certainly lished book, Vegetable Moula and not less startling and suggestive than Earthworms, this acute observer has those derived from the study of land shown that, in many parts of England, surfaces. We propose in the present the mould which in the course of a article to give some account of the latest single year passes through the bodies of results which have been arrived at conearthworms weighs, when dried, ten tons; cerning these curious operations, and at or, in other words, that the worm-casts the same time to indicate certain fields thrown up annually on a square mile of of research in which future investigators surface amount to no less than 6,400 may be expected to gather abundant tons of dry earth! Mr. Darwin justly harvests. The publication of the latest remarks that, at this rate, the whole of the Challenger Reports on “ Deep soil of the country must in a few years Sea Deposits,” by Dr. John Murray, pass through the bodies of these organ one of the naturalists on board the exisms; and he shows how not only the ploring vessel, and Professor Renard of burying of neglected cinder- and gravel. Ghent, a very able geologist, has suppaths, but the covering of mosaic pave- plied us with a great body of interesting ments and ruined walls, no less than the facts, admirably described and classified, preservation of coins and other objects while many scattered papers by these of art so precious to the antiquary, authors and by Mr. Buchanan, who acinust be ascribed to the unceasing action companied the Challenger in the capacof these little-regarded creatures. Fur- ity of chemist, suggest numerous interther than this, he calls attention to the esting lines for thought and speculation. fact that the fertility of the soil itself A little consideration will show that is largely due to the same cause. The all the known chemical elements—and body of each earthworm constitutes a even the unknown ones too-must be mill, in which the mineral matter of the contained in solution in the waters of soil is reduced to the finest state of sub- the ocean. Rivers flowing over the land division, while it is intimately admixed are continually taking up mineral matwith organic materials ; it is at the samne ter in solution, and these substances are

all added to the mass of materials dis- of extracting and concentrating comsolved in the oceanic waters. The pounds of the rare element from the Thames every day carries to the North great mass of water in which they are Sea some 2,000 tons of dissolved ma diffused. Many other substances, such terial, and if all the rivers of the globe as sulphur, phosphorus, iron, and others work at something like the same rate, of the metals which occur abundantly 20,000,000 tons of mineral matter must in the ashes of plants and animals, but day by day be added to the store of ma which are found, if found at all, only terials held in solution by the ocean. as the minu test traces in sea water, must Now, all the chemical elements are have been isolated from it by the same capable of entering into compounds selective action of plants and animals. which are to a greater or less extent sol- It is this power belonging to all plants uble in water, and hence we cannot and animals, from the lowest to the doubt that in the enormous mass of highest, which accounts for the presmaterials dissolved in the vast body of ence of minute quantities of the rarer sea-water on our globe all the elementary chemical elements in organic tissues. bodies must be represented.

Thus our bones are largely built up of It is true that the chemist, by his a compound of phosphorus, while our most refined methods of analysis, is un- teeth contain, in addition, fluorine. able to detect the proportion, even if he Analysis of the food we eat and of the is able to determine the presence, of the water we drink shows that the former rarer elementary substances which oc- element exists only, when present at all, cur only as “minute traces” in sea- in very minute quantities, while all the water. When a large quantity of sea most delicate tests at our command water is evaporated, we get a mass of would probably fail to reveal the existchlorides and sulphates that can be sep- ence of the latter substance in either arated by analysis ; but even the very food or drink. delicate tests of spectral analysis fail to There are several mineral substances make manifest many of the rarer metals which are found only in minute quantiand other elementary bodies that must ties in the oceanic waters, but that are, certainly be present in the mass. In a nevertheless, separated from the water well-known case, the copper sheathing by various plants and animals which of a vessel has been proved to have have the power of concentrating them taken up silver from the sea-water by in their skeletons ; and on the death of electro-chemical action, though it is the organism the mineral matter of the probable that all our ordinary analytical skeletons is left behind to build up great processes would have failed to reveal rock-masses. Chief among these subthe existence of the metal in the water stances so separated from sea-water is itself.

carbonate of lime. Careful analyses There is another way, however, in have shown that sea-water seldom conwhich the presence of certain of the tains more than 1 part in 10,000 by rarer elements in sea-water inay be ren. weight of carbonate of lime. Yet the dered manifest. When plants and ani- myriad forms of foraminifera, corals, mals which have lived wholly in the echinodermata, mollusca, and other waters of the ocean are burned, so as to forms of life find in this minute proporremove the organic matter, a mass of tion of material all that is necessary for ash remains in which many rare chern- the growth of their skeletons. In all ical substances may sometimes be de- parts of the ocean except some of the tected. Thus an ordinary analysis of very shallow and the extremely deep sea-water, or of the salts derived from areas, great numbers of calcareous orit by evaporation, may reveal only the ganisms live and multiply, and in the merest traces of iodine, while, as is well warmer regions of the ocean a constant known, certain seaweeds yield so much rain of calcareous matter is continually of this element in their ashes that until falling upon the ocean-floor from the lately they constituted the largest, and death of the organisms which float in indeed almost the only, source of the prodigious abundance at the surface and element. In such cases it is clear that intermediate depths. It can be shown the organisms must possess the power that the limestones of the earth’s crust,

which not unfrequently attain a thick- number of the elements have been deness of thousands of feet, and cover tected in these ashes-must have been areas measured by thousands of square extracted, in some form of combinainiles, must all, with very few excep. tion, from sea-water ; being taken by tions, have been formed by the agency the organism either directly from the of plants and animals.

medium in which it lives, or indirectly Silica is present in sea-water in much in the food passed through its body. smaller proportions than carbonate of Recent observations of very great inlime. It is, indeed, difficult to obtain terest bave shown that, even in those any estimate of the proportions in which cases where carbonate of lime seems to natural waters contain this substance. be separated from water by purely chemCertain investigations of Forchammer ical agency, living and growing plants point to the conclusion, however, that really play an important part in the procsilica is never present in sea-water to the ess. În the formation of those masses extent of 1 part in 50,000, and that of calcareous rock known as travertine, probably 1 part in 100,000 would be a which are left behind when springs of very liberal estimate indeed. Neverthe- water highly charged with carbonate of less, those minute plants the diato- lime flow out at the surface, the cause maceæ, with the animals known as of the deposition has usually been held radiolarians, and siliceous sponges, er- to be the evaporation of the water and tract the minute proportion of silica the escape into the air of free carbonic from sea-water to build up their ex- acid from it. But the eminent German quisitely beautiful skeletons, and these, botanist, Professor Ferdinand Cohn, has on the death of the organisms, accumu- shown that the really efficient agents in late to form great masses of siliceous removing the free carbonic acid, which rock.

holds the mineral matter in solution, Phosphate of lime is probably not are numerous minute and lowly plants, present in greater quantity in sea-water and that around these plants the solid than silica, yet the bones of fishes and matter is deposited, as the water is ren. the shells of crustacea and other organ- dered incapable of longer holding it in isms are largely composed of this sub- solution by the action of the living orstance; and, as is shown in the in- ganisms. A very curious fact pointed teresting Challenger volume to which out by this observer is that these minute we have referred, very important de plants are active agents in the formaposits of this substance are being formed tion of the pisolitic deposit of Carlsbad on many parts of the ocean-floor. (the Sprudelstein), and that the organ

Salts of iron, though present in sea- isms which in this case perform such an water, must exist in very minute quan- important work are capable of living at tities. The same is true with respect to a very high temperature ; they flourish, the waters of rivers and lakes ; yet com- in fact, in waters only a few degrees bepounds of this metal are extracted from low the boiling-point. their state of solution in water by vari It is a well-known fact that the waters ous organisms, in the remains of which of the hot springs of the Yellowstone they may easily be detected by analysis. National Park in North America, and In the case of the pisolitic ores found on the siliceous and calcareous materials the beds of the Swedish lakes, we have deposited by them, owe their brilliant an example of what can be done in sep- and varied colors to the numerous forms arating salts of iron from a state of solu- of plant-life that multiply and grow in tion by a very lowly organized plant, the waters, even when at very high “Didymohelix” (the Gallionella fer- temperatures. Whether the deposition ruginea of Ehrenberg). The crop of of silica, as well as of calcareous matiron-ore, if removed from the bed of the ter, is in any way aided by the action of lake by dredging, is renewed in the these growing plants—as has been maincourse of a few years by the growth and tained by certain American observersmultiplication of these plants.

is a point on which some difference of In the same way, all the elements opinion still exists. which occur in the ashes of marine The mention of the pisolitic masses plants and animals—and a very large of Carlsbad cannot fail to suggest to the

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geologist the question of the origin of that may accumulate to form great rock those widely distributed limestones masses. known as oolites” or “roe-stones,” It is very interesting to note that which are found in all the formations while certain plants are thus engaged in of the earth's crust, from the oldest to building up limestone rocks by investing the youngest. Many years ago Sir minute shells and shell-fragments with Henry De la Beche pointed out that successive layers of calcareous material, very similar rounded grains to those other organisms of the same class are composing our Portland, Bath and Ket- occupied in a work having an exactly ton limestones are being, formed at opposite tendency, namely, that of borthe present day, on tropical shores, ing into and dissolving away the subespecially around coral-reefs, and his stance of calcareous organisms. The observations have been confirmed by late Professor P. M. Duncan called atNelson and other investigators. Sorby, tention to the fact that fossil corals and by a study with the microscope of thin other organisms are frequently found to sections of the recent grains and their be perforated by fine tubes, and his conanalogues of former geological periods, clusion that these tubes were produced has demonstrated their substantial by a parasitical vegetable organism, identity. All the early observers seem which in its growth dissolves away and to have concluded that in the shallow thus penetrates into calcareous skelepools and lagoons about coral-reefs an tons, was confirmed by several observers. actual deposition of calcareous matter More recently the able French algolomust be going on, owing to the evapora- gist, Ed. Bornet, has shown how abuntion of the sea-water, and the escape dant are organisms possessed of this refrom it of free carbonic acid ; and that, markable power, and how widespread in consequence of this concentration, and striking are the proofs of their acminute shells and other objects become tivity. It is difficult to find a fragment centres around which successive layers of shell, coral, or bone, either in the acof carbonate of lime are deposited. But cumulation now taking place on the very careful microscopical study of ocean-floor or in those which have been preparations of the modern and ancient formed during earlier periods of the oolite grains reveals the fact that they earth's history, that is not riddled in all exhibit traces of curious folded and directions by these curious perforations ; branching tubes, and there is the strong- and in many cases the calcareous masses est ground for believing, that as in the have their whole substance so completely structures so well described by Cohn, eaten away in all directions that they the deposition of carbonate of lime is crumble to powder at the slightest touch. aided, and perhaps entirely effected, by It is obvious, therefore, that these plants the agency of minute vegetable organ- must play the part of scavengers, peneisms. Mr. E.

Mr. E. Wethered has indeed trating into and dissolving away the shown that, in the limestones of all ages fragments of shells and other calcareous those obscure organisms, consisting of organisms on the ocean floor, and thus twisted and sometimes branching tubes leading to their complete disintegration —which have received the names of and removal. Bornet has not only deGirvanella, Micheldeania, etc. are scribed a number of genera and species very abundant, often making up large of these burrowing plants, differing froni portions of the calcareous mass ; and one another greatly in the forms and that these organisms are plants which characters of the tubes which they exhave the power of secreting calcareous cavate, but he has performed a task of matter within their cell-walls or of much greater interest and importance in causing it to be deposited outside them, working out the life-history, habits, and is now maintained by botanists of wide modes of reproduction of these singular experience and knowledge. It can and hitherto unknown members of the scarcely be doubted that in salt-water vegetable kingdom. no less than in fresh-water the growth Åmong the most interesting of the of plants taking up carbonic acid leads problems brought into prominence by to the deposition, within or outside the researches carried on during the their tissues, of calcareous material Challenger and other deep-sea exploring

expeditions is that of the origin of de are certain areas, like that off the East posits of iron and manganese among the coast of South America, where red and materials found upon the ocean-floor. variegated tints, like those of our Trias, Most of the muds upon all but the most Permian, and Plastic-Clay formations, profound portions of the ocean bed are are found to prevail. In these cases the characterized by a deep blue color, and iron is evidently in a different state of the analyses of Mr. Buchanan have oxidation and combination to that of shown that this blue color is due to the blue clays. In all the deepest porfinely divided iron disulphide (iron tions of the ocean, similar tints of red pyrites). The surface layer of such and chocolate brown characterize the muds may have a brown tint from the argillaceous deposits, that seem to be oxidation of the iron, but the deep blue very slowly accumulating there. There tint is almost always found below the in evidence that even at these extreme superficial brown layer. The same depths (3,000 to 4,000 fathoms and upcolor, as is well known, prevails in most ward) living beings exist in considerable of the argillaceous, and in many of the abundance, in spite of the extreme cold, calcareous and arenaceous deposits of the the great pressure, and total absence of earth's crust; and the blue color of such light. So that the separation of the masses of clay as constitute the Lias, the iron from its state of solution may even Oxfordian, the Kimeridge, the Gault, here be due to the action of living and the London-clay formations have organisms, though the slowness with long ago been shown by Ebelman and which accumulation takes place leads to Church to be due to the dissemination the oxidation of the iron. through their mass of iron-pyrites in a On these deepest parts of the oceanvery finely divided state.

floor, however, we find very remarkable It has been shown by Mr. Buchanan chemical deposits, which may well enthat the formation of the iron disulphide gage the attention of chemists and geolin the blue inud of the ocean-floor, is ogists, as throwing light upon the curidue to the action of the innumerable ous actions taking place in the profoundmarine worms that pass the fine mud est recesses of the sea-bed. through their bodies, and throw it out these we may mention the curious crysin the form of worm-casts. Within the talline masses of zeolites, that are somebodies of the worms, chemical action is times found scattered throughout the continually going on, sulphur being sep- red mud, and occasionally forming no arated from the sulphates dissolved in inconsiderable proportion of its mase. the sea-water to form sulphuretted These zeolitic minerals are known to hydrogen, while iron, extracted from geologists as the constant result of the the water by the breaking up of the car- action of water upon the silicates that bonate, unites with it to form the iron compose volcanic rocks, and are usually disulphide. The foul smell of these found in the steam. holes and other cavimuds when they are first brought to the ties of lavas, which through long periods surface in the dredge affords evidence of time have been subjected to the action of the chemical action going on in them. of permeating waters. Daubrée has Mr. Buchanan has justly dwelt upon shown that the same minerals have been the similarity of the operations taking formed at Plombières and other localities place upon the ocean-floor, in conse- during historical times, by the action of quence of the action of marine worms, more or less heated spring waters upon to those which Darwin has so carefully the brick and concrete-structures studied upon the terrestrial surface as erected by the Romans to serve as conresulting from the action of earth- duits for them. The chemical action worms. In both cases we recognize an which produces these zeolites on the impressive illustration of the action of ocean-floor must take place at temperaseemingly insignificant agents in pro- tures but little above that of the freezducing results of the greatest magni- ing point of fresh water ; but it is not tude.

improbable that the great pressure, While the clays in the less profound amounting to between three and four portions of the ocean-floor are, as a rule, tons to the square inch, may

be a subcharacterized by a dark-blue color, there stitute for the want of an elevated tem

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