spoken of. Hence, if the tops of the corrugations only are in focus, they appear as bright circular beads at pretty regular distances upon a number of indistinctly defined bright lines running down the scale longitudinally, but which sometimes anastomose with each other. A little deeper focussing dissolves this view, in which I think "the spherule theory" takes its origin, and converts the bright dots into "note of exclamation" markings nearly consecutive with each other. The scale then appears to be scored with ridges, like the exterior of one of the valves of a cockle-shell, but nevertheless it bears considerable likeness to the test scale-the scale of Lepidocyrtus Curvicollis. (See Fig. 5.) In the scale of Lepidocyrtus I recognize the same plan of structure, and would account for the peculiarities of its appearance by the more frequent anastomosing of the corrugations and the greater minuteness of the costa, which structure renders it more difficult to trace the course of the ribs. Microscopists generally also I think, fascinated by the beauty of the exclamation markings, have devoted all their efforts to the development of this appearance, and have neglected to a great extent to read the structure of this object as interpreted by transmitted light at a very oblique angle with the stage, and other modes of illumination at their command, because these modes alter the view to one much less captivating. I will say no more respecting this scale, since I can add nothing to the accuracy or clearness of Mr. Beck's observations on the subject* beyond expressing my belief that the "beads" are only the most elevated points on the surface of the scale, which can be focussed alone, the slightest alteration of the focus dissolving them into the note of exclamation markings. In the scale of the Speckled Podura, Degeeria domestica of Nicolet, a scale which I prize very highly for its beauty, I seem to find support in the opinion of the structure of the scale of Lepidocyrtus that I have formed. The insect is rare in England, but I have reason to think its scales are often sold on the Continent, where it is probably more abundant. The scale claims strong affinities with the other Podura scales that I have mentioned in the single characteristics it presents to the view; but in uniting these features in itself it is unique. For instance, it has minute cross-striæ like Macrotoma, the costa are interrupted, and tend to overlap each other as in the Greenhouse Degeeria, while by direct transmitted light it exhibits the "note of exclamation" markings of Templetonia and Lepidocyrtus very beautifully; but in uniting all these features in itself it presents a perfectly distinctive character.† Quarterly Journal of Microscopical Science.' Occasionally, too, on certain scales the ridges anastomose very distinctly, and at these points certain illumination will give an appearance not very remote from the so-called spherules or beads of Lepidocyrtus. According to the nature and direction of the illumination so the view of the markings is greatly changed, and it would be quite impossible except by the aid of photography satisfactorily to represent all the appearances it is possible to obtain. I have chosen one view for representation (obtained by illuminating from below the stage at a wide angle), in which some idea of the real structure of the surface of the scale and the relation of the markings to each other, according to my opinion, is attempted to be shown. (See Fig. 6.) To sum up, then. I do not believe that the Podura scale consists of globular beads placed at pretty regular intervals between two membranes. I believe it to be a case of "one apparent exception proving a rule," and that rule is, that the markings of the scales of insects, except where iridescence or the presence of pigment claims attention, are wholly due to corrugations of the membranes. So far as I can judge, I believe both sides of a Podura scale are alike, and I have examined the scales uncovered as opaque objects with high powers. This proceeding is very difficult, and not wholly satisfactory, but I think I have seen enough to form an opinion upon it. I have never been able to separate a Podura scale into upper and lower lamina; but there is every reason, I think, to believe that, as with the scales of other insects, there are two. For instance, in the scale of the Diamond Beetle (Eupholus), when detached and viewed by transmitted light, one lamina is seen to possess the iridescence and the other is transparent; and it has happened to me in endeavouring to obtain the scales from the wing of a species of Morpho in my possession, that single scales have been split, one lamina, the upper one, which readily comes away, being strongly corrugated and nearly translucent, and the other, which it was not so easy to detach from the wing, being intensely blue, and possessing extremely minute longitudinal striæ. * This remark is equally true with regard to all the Podura scales, as Mr Beck's figures of the scale of Lepidocyrtus testify. II.-Organisms in Mineral Infusions. By C. STANILAND WAKE, F.A.S.L. (Read before the ROYAL MICROSCOPICAL SOCIETY, December 8, 1869.) AT the present time, when so much is being said and written about "spontaneous generation" and the conditions of life, there is no wonder that the mind sometimes, almost involuntarily, turns towards the "inorganic" world, and wonders whether the rocks whose origin is due to the activity through countless ages of microscopical organic creatures, may yet be made to restore some part of the vitality they have absorbed. The idea that this might be so led me to make the experiments the results of which I am about to detail. My first experiments were with coal. The character of this mineral, and the varied and curious products which have been derived from it, make coal much more promising than any other of the organic minerals as a subject of investigation. There are, however, two conditions absolutely necessary (as will be well understood) to success. Life requires moisture for its development, and this moisture can be properly applied for the object had in view only when the coal or other mineral has been disintegrated, and its particles are made as fine as possible. When a piece of coal has thus been finely divided and its constituents placed in water, it will be found, when examined under the microscope, to contain (besides the larger pieces of black matter) irregularly-shaped black or brown particles, like portions of fronds, small pieces of crystalline substance-generally of a greyish hue, but often marked or mottled with brown—and numerous minute dark bodies, many of which are apparently of an oval form, the smaller ones having a rapid and regular vibratory motion. When an infusion of coal presenting these characters, made with distilled water, had been allowed to stand about a week, I examined some of the coal powder under the microscope, and found that a curious form of vegetation was beginning to be developed, sometimes from the larger black pieces of matter, but generally from the crystalline substance. This vegetation ultimately formed masses of irregularly-shaped stems, bearing one or more fronds, and its black colour and curious formation gave it a very strange appearance. This, however, is not the only form. of vegetable growth to be met with in this infusion. Sometimes I have found fibres, apparently flattened and perfectly black, which occasionally attain great length. Other fibres resemble these, except in colour (which is of a greyish hue), and in their bearing at intervals, small black fronds. I have several forms of this grey fibre, in one of which the sides are indented at regular intervals, Microscopical giving the appearance of its being composed of a series of cells, and in another instance two fibres seem to be plaited together. The latter is very beautiful, and more uncommon than the indented form. I before remarked that the vegetable growth generally springs from the crystalline substance. This is not surprising; for masses of this substance are often seen attached to the foliage of the vegetation, as though it were a result of fructification. In addition to this, there is a considerable quantity of gelatinouslooking substance, which appears to exude from the coal matter, or to be in some way connected with its growth, and which, although sometimes beautifully clear, often has a speckled appearance. The explanation of the speckled appearance I do not know, but occasionally a number of the small dark bodies above referred to are collected very near to the substance in question, as though they have some relation to it. Other phenomena connected with the coal infusions are the presence of small crystalloid bodies which float about freely in the water, and the projection of minute moving protuberances from various parts of the coal-substance and vegetation. As to the former, there is little to say beyond that they are not angular, and that one side which is less curved than the other is usually distinguished by a dark line at the margin. The protuberances, which sometimes take the form of " tubes," and at others of broad indented limbs, somewhat resembling what I have seen in other infusions to be mentioned, are of a dark colour. From their movements they appear to me to have relation to animal rather than to vegetable life, although they certainly are attached to the vegetation, often several tubes being together at the end of a frond. Occasionally a tube is much larger than usual, and then the movement is very perceptible, and on one occasion I observed distinctly the protrusion of a "tongue," which moved rapidly from side to side. These phenomena are not limited to any particular coal. I have experimented with Cannock deep (Staffordshire), Swaithe (Barnsley), Glyn Neath, Wigan, and Anthracite, all of which give analogous results, although, perhaps, the non-bituminous Cannock deep coal and that from Wigan show a more luxuriant vegetable growth. It will be thought that whatever vitality the vegetation of the coal-beds may have retained, there can be no hope of producing life, vegetable or animal, from chalk. The chalk with which I have experimented was obtained from a well-boring in the Hertfordshire hills, and it consists of minute organisms of various forms, some round, others like straight or curved tubes, and many bodies resembling the ovate coccoliths so distinctive of the mud from the Atlantic depths. A number of minute moving bodies closely resemble, except in colour, those found in coal infusions. When this chalk, after it had been finely powdered and kept in water for some days, was examined under the microscope, tube-like protuberances were found to have been formed from the larger masses, and these had a movement like that of the tubes of the coal infusion. But this is not all. The particles generally presented the appearance of having a gelatinous coating, and in the course of several weeks they showed a tendency to become agglomerated, the mass having small bud-like projections at various points, the extremities of which are occasionally seen to move. These projections after a time become larger and irregular in form, and their movement is then much more perceptible. In fact, at the present moment the chalk of that infusion is, so far as I can judge, in a state of perfect vitality. It is evident from mere inspection with the unassisted eye that a change has taken place in the chalk, as what was at first a fine powder is now coarsely grained owing to the agglomeration of the particles and the elaboration, doubtless, of fresh cretaceous matter by its busy inhabitants. Independently, however, of this, there is other evidence of life. This evidence is furnished by the numerous small detached organisms which move freely through the fluid, and by the existence of very small white bodies, which can be seen rushing about over the microscopic field, especially after the slip has remained moist for twenty-four hours. A more curious proof, however, is found in the presence of what I can only suppose is a vegetable growth. This vegetation is in the form of long, flat, semi-translucent fibres, not unlike the grey fibres of the coal, but, judging from the shading, having sometimes a slight tendency to the spiral form. There does not appear to be any development of "foliage," but at various points there are chalky accretions, and occasionally the fibre is covered with these throughout its entire length. If the recovery of organic life from chalk be strange, such a result in relation to marble must, considering the greater density of this mineral, be far stranger. When a small piece of this mineral is finely powdered, it appears to consist of crystals, with numerous minute particles in active movement. When, however, the marble has remained infused for some weeks, many of the crystals have the appearance of being covered with a gelatinous substance, from which various small "buds" have been produced. Some of these buds are longer than others, and move to and fro like the tubes in the coal infusion. Ultimately, however, there is so great a development of the coating substance as often to quite conceal the form of the crystal, accompanied by that of numerous small bodies of various sizes, some of which have much the appearance of the "buds" at first observed. These are evidently of the same character as similar bodies found in the chalk, and they sometimes form irregular moving projections such as those referred to as being produced in the chalk infusion. Other larger formations resemble the "finger" shaped organisms I shall have again to mention in connection with an |