cover with thin glass, and apply very slight pressure, so as not to smash the crystals. To my surprise I did not find in any of these a single aigrette, but multitudes of more or less amorphous masses, tending to regular crystalline forms. A few of these masses, but by no means the smallest, are given in the annexed sketch, and it will be seen from the appended statement of magnification, that they were very small in comparison with the aigrettes in the first specimens. The aigrettes were beautifully shown with a one-fifth objective and second eye-piece, giving a power of 420, while the examination of the amorphous masses was advantageously made with Smith and Beck's one-twentieth and first eye-piece, giving X 420 X 1000 X 1000 CRYSTALS IN INTESTINE OF ARTEMIA SALINA. 1000 linear, and manipulated with quite as much facility as the lower power. Although this high magnification was necessary for accurate examination, the amorphous particles could be discerned with as low a power as two hundred and thirty when the attention was directed to them. In many cases the intestine was nearly filled with these particles, which in the aggregate exceeded in quantity the dark focal matter. The approximation to regular form of crystals varied greatly in different individuals. In some, every particle might be described as amorphous ; in others, many imperfect crystals could be seen, and in one I noticed two regular hexagons; one of them such as would be obtained by inscribing a hexagon in a circle, and another such as would result from applying a right angled triangle to each of the smaller ends of an oblong figure. Both of these were exceedingly small, and required the one-twentieth for their adequate display. Referring again to plate 8 of the Micrographic Dictionary, the reader will see, in fig. 2 a, how a hexagon may be formed by the coalescence of two rhombs, and two half rhombs, or triangles, of uric acid. I looked in vain for perfect rhombs in my specimens, but Professor Tuson, to whom I gave some of the second batch of Artemia, discovered some in his. It would be absurd to place much faith in generalizations drawn from a few observations, but it is curious that my first supply of brine shrimps, containing the aigrettes, lived for some weeks in confinement, and mostly perished through microscopic examination, while the second supply, containing the amorphous lumps, died off very fast. Does the amorphous condition indicate a rapid deposition, arising from an excess of uric acid incompatible with the little animal's well being? Living far away from the Hampshire brine pans, I cannot expect to unravel the difficulty; but where there are brine pans, there are no doubt "Intellectual Observers," and I hope some of your readers will give to this curious question the attention it deserves. I should also like to know whether crystalline forms are common in the intestines of other marine entomostraca, and whether their appearance at all, or only their appearance in excess, is a symptom of bad health. I cannot believe that concretions, relatively large in proportion to the intestine, can be productive of comfort, and some of them were so stuffed up with angular particles as to suggest the idea that a visit from Dr. Civiale, with an apparatus adapted to microscopic lithotrity, would have been a desirable event. On the 19th July I had only one Artemia left, and it was still very lively; but on looking attentively into the bottle it appeared to have acquired a famous long tail, which it swished about as it went. A pocket lens explained this appearance, and showed nine cylindrical pellets of fecal matter, equidistant from each other, and held together by some transparent material. The pellets proved, on examination, to be full of amorphous particles, but I could not succeed in making out how they were strung together, whether by a thin membrane carried away from the intestine, or by a mucous secretion. I relieved the Artemia of this strange appendage, and it seemed none the worse after being replaced in its bottle. I have called the deposits uric acid, but I had not enough of the material for definitive experiments. Professor Miller states, in his Elements of Chemistry, that "uric acid crystallizes in rhombic tables, the outlines of which are frequently rounded; but when it is deposited from animal fluids the form of the crystals is often much modified." The same authority says that "pure uric acid is a white crystalline powder, requiring 10,000 parts of cold water for its solution." This being the case would account for no harm being done to my crystals by immersing them in drops of fresh water. The urates, although sparingly soluble, are much more so than uric acid. Urate of potash (neutral) is soluble, according to Miller, in forty-four parts of cold water; the urate of soda is somewhat less soluble, and the urate of ammonia is soluble in 1800 parts of cold water. The Micrographic Dictionary gives drawings of crystals of urates, none of which correspond-as some of its representations of uric acid do-with those in the Artemia, but it adds that their forms "are not very characteristic." In the article Uric Acid, in the same work, it is observed that "the crystals forming a natural deposit are almost invariably coloured, from combining with the colouring matter of the urine." Little crustaceans like brine shrimps would not be expected to colour this substance, and in all my specimens it was pure white, like glass. I should recommend anybody looking for these crystals to cut off the abdominal segments before using any compression. If the entire animal is compressed, too much mess is made to see them clearly, and unless the abdomens are placed in clean fresh water, the observer is pretty sure to be troubled by the deposit of salt from the strong brine in which the creatures dwell. THE COLUMNAR BASALT OF POUK HILL, BY J. JONES, Secretary of the Dudley and Midland Geological Society. WE are so accustomed to regard the Giant's Causeway, and Fingal's Cave in Staffa, as the only British examples of columnar basalt, that perhaps the title of this chapter may appear indicative of some new discovery. This is not the case, however, for the peculiar columnar structure of the igneous rocks which occur in connection with the coal-measures of South Staffordshire, and also of the Clee Hills farther west, has been long known and recorded; but the face of basalt, which is now exposed at the extensive quarries of Pouk Hill, near Walsall, affords, perhaps, a finer section of this remark The hill able structure than has ever been exhibited before. is situated near the high road from Walsall to Willenhall, and about two miles from the former town. The basalt at this place seems to have been originally protruded from the neighbourhood of the Rowley Hills, about six miles distant, perhaps shortly after the formation of the lower coal-measures, for in an open working of the bottom-coal, to the south of the quarry, the basalt is seen reposing on the coal itself, which has been changed by contact into anthracite. In another section, exposed by cutting a tramway from the quarry, coal shales are seen to rest on the igneous rock, but they have not undergone any change; hence it is tolerably certain that the protrusion of the basalt took place immediately after the formation of the Bottom coal of the district. Mining operations have recently been carried on completely under the knoll of basalt, and no trace of any pipe or vent through which the stream of molten matter could flow has been discovered. Hence it is now generally admitted that the stream must have had its origin farther to the west, and after passing through the lower coal-measures some distance, it found an opening, and thus formed a large mound of igneous matter. The composition and mineral characteristics of this basalt are the same as that of the more remarkable localities in Scotland and Ireland. The central part of the mound has been long worked away; but, from the general arrangement of the columns, and the way in which they curve towards a point which would be directly over the middle of the quarry, there is reason to believe that the columns radiated regularly from the cooling surface of the basalt, and in the interior of the boss, assumed a vertical position. The workings on the north-eastern side show these vertical columns for a space of about thirty yards, and many of them are upwards of twenty feet in height. They are of a rude pentagonal form, and in some cases above two feet in diameter. Towards the top of the section the columns are smaller, and bend over with great regularity. A few months ago the Midland Geological and Scientific Society held one of their usual field meetings at the quarry, and examined carefully the geological features of the locality. The material is extensively used for road-making and paving in the neighbourhood. At the works of Messrs. Chance, glass makers, near Birmingham, this basalt has been melted and cast into candlesticks, vases, and other articles, which take a tolerably high polish, and somewhat resemble in appearance the black Derbyshire marbles. The mass of basalt at the Rowley Hills has also been extensively quarried for road purposes, and the largest excavation shows a very rude columnar arrangement of the igneous rock, but not nearly so well defined as that of Pouk Hill. Of course, we are not maintaining that the regular and beautiful appearance of the Isle of Staffa, or the north of Antrim, is reproduced in South Staffordshire; but the approach is so near in the case of Pouk Hill that it seems worthy of more than mere local record. A few years hence, and the quarry will doubtless be worked out; and indeed we very much question if a section equal to the one recently exposed will again be witnessed, as the basalt is being rapidly exhausted, and hardly a day passes without some of the columns being demolished. PASTEUR'S RESEARCHES ON PUTREFACTION. THE following paper was read before the French Academy on the 29th June, and will be found in the Comptes Rendus for that date: "In every case in which animal or vegetable matter undergoes spontaneous alteration and develops fetid gases, putrefaction is said to occur. We shall perceive in the course of our examination that this definition has two opposite defects. It is too general, because it brings together phenomena that are essentially distinct; and it is too restricted, because it separates others which have the same nature and origin. "The interest and utility of an exact study of putrefaction has never been misunderstood. Long ago it was hoped it might lead to practical consequences in the treatment of maladies which the old physicians termed putrid. Such was the idea that guided the celebrated English physician Pringle when he published, in the middle of the last century, his experiments on matters septic and antiseptic, with a view to illustrate his observations on the diseases of armies. "Unfortunately the disgust inseparable from labours of this kind, joined to their evident complication, has hitherto arrested the majority of experimenters, so that nearly everything has still to be done. My researches on fermentation have naturally conducted me towards this study. The most general deduction from my experiments being that putrefaction is determined by organic ferments of the genus Vibrio. Ehrenberg has described six species of vibrio, to which he gives the following names: 1. Vibrio lineola. 3. Vibrio subtilis. 4. Vibrio rugula. 5. Vibrio prolifer. "These six species, in part recognized by the first micrographers in the last centuries, have been since seen by all who |