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ever, been mounted for sale, but they well merit attention; and though on close examination their markings are found to be similar to those on the test scale, omitting all consideration of the
and many died. I therefore liberated those remaining in the cellar whence their parents were obtained, lest the species should be exterminated. I have tried several times since, without success, to keep this species in confinement : they always pine away and die; and though they will eat oatmeal, they do so but sparingly. 4. The progeny of both kinds of Poduræ were very numerous in their native haunts on the 1st of October. Possibly the dampness of the past summer had promoted their increase. In several places the under sides of certain boards swarmed with the black species, and their exuviæ were equally abundant in the same situations.
Fig. 46. White Podura (Lepidocyrtus Albinos ?).
Fig. 45. Scale of Speckled Podura, by reflected light, small
side ; condensing lens, $ objective, C eyepiece.
Fig. 47. Scale of White Podura ; $ objective, A eyepiece.
About the 6th of June nine of these insects were inclosed in a cell, and on the 16th I noticed that about sixty globular eggs were laid. On the 24th of the same month, the eyes of the contained young might be perceived through the shells, which burst on the 27th, and permitted the young to make their exit.
These are lively from the first, and resemble their parents in all, saving that they appear to be very delicate and destitute of scales.
While the young of the black Poduræ seemed to be quite comfortable in the damp cell, these appeared soon after to be in an unhealthy condition,
of the scale-bearing Poduræ. It seems to be very partial to the vicinity of flower-pots, and underneath them it may often be found. One specimen was damaged in being captured, two of the joints of one antenna being broken ; but in the course of ten days the damage was repaired, and the one antenna was almost the counterpart of the other. The scales, which were first described to me by the late lamented Mr. Richard Beck, are very thin ; but notwithstanding this the markings are very
distinct, and have a great tendency to follow each well with a good half-inch objective, assisted by the other in longitudinal rows. In order to give a condenser and a deep eyepiece; but, althoagh they rough idea of their ap pearance comparatively with are said to be visible with a one-inch, it is only, to others we attach a figure, exhibiting them as seen quote from Dickens, when you “make believe very under an fth object-glass. In Mr. Beck's beautiful much ” that the mottlings then seen are comfortably paper in the Microscopical Journal, on the subject of resolved.
Fig. 50. (Same>
Fig. 49. Scale of Speckled Podura, oblique illumination.
Fig. 48. Test Podura Scale; upper portion, $ objective,
A eyepiece; lower portion, to objective, C eyepiece. the Scale of Lepidocyrtus, he says : “The best scales are obtained from the insects found in comparatively dry places.” So far, and in some other particulars, I find our experiences agree. His speciality (which we figure as the “test scale") is either a variety of the black Podura or a distinct species; most probably the latter. The outlines of Podura scales are very different in different species; and although there are many erratic shapes, those drawn will, we think, be found to be the forms which predominate. The drawings of the scales have all been made with the aid of Ross or Beck's object-glasses and Powell and Lealand's achromatic condenser (170°). The markings can be seen without an achromatic condenser ; but the view is infinitely more satisfactory when this apparatus is used. I have also employed Smith and Beck's, which is admirably adapted for exhibiting them. A moderate aperture only is requisite, both in the object-glass and the illuminating apparatus, for their perfect display; but the workmanship of the objective must be of the best description. Any error in the correction of the lenses, whether in the manufacture or in their adjustment for penetrating the thin covering glass, is immediately betrayed by the peculiar appearance which the markings present. Mr. R. Beck has dealt with this subject so thoroughly in the paper I have alluded to, that I hardly feel competent to speak on it.* I have seen the markings moderately
An object-glass, wbich will show the Podura scale perfectly, may be predicted to be capable of being employed satisfactorily on the easier diatoms, such as P. angulata and P. hippocampus ; but it does not follow that another glass, which will show the striæ on the N. rhomboides, Surirella, P. fasciola, N. cuspidata, &c., will perform equally well on the Podura scale. It is possible, however, for a good high-power glass to be equal to both these requirements. Amateur mounters should cover the scales they put up with the thinnest possible glass, so that, when opportunity offers for an examination of the slide under a remarkably good *th or tath, they may not find themselves doomed to disappointment, owing to the inability of the objective to penetrate the thick cover.
In conclusion I beg to offer a few remarks on the scale of the Speckled Podura. As I have stated above, it possesses transverse striæ, and these are rendered most distinct when the central rays of the achromatic condenser are stopped out. I believe that the structure of Podura scales in general may be best studied in this one. From very careful examinations I have no doubt that the
* I refer more particularly to the accepted standard test scale,
surface is uneven, and believe that its irregularity is
ANALOGY OF SMELL. the result of both upper and lower membranes
A N article on the “ Analogy of Form " in the being folded into a number of minute pleats or
A last number of SCIENCE Gossip, brought to wrinkles, which have a tendency to overlap each other—a difference in detail only, not in plan,
my mind the very remarkable instances which are between these markings and those on the scales of
to be found in the Analogy of Smell among the Fungi. I have lately been turning my attention to these interesting productions of nature, and have often been quite astonished at the exact resemblance which the odours of certain species have borne to something extremely familiar to me, but of a totally different nature.
During the month of October last, as I was ascending one of the rising slopes of the Cotteswold hills, in the vicinity of Cheltenham, I thought I perceived the peculiar but agreeable scent of Russian leather, and recollecting that there was a fungus reputed to possess that odour, I immediately directed my search for it. Several specimens were
growing around me where I stood, and thus I had Fig. 50. Scale of Podura, unknown species, x 450. been led to detect this little white fungus by its
scent, as we sometimes do the violet in the spring all other insects. This is best shown by oblique of the year, before the eye reveals its whereabouts. illumination; but when the illuminating ray is in a The Rev. M. J. Berkeley says of this species direction corresponding to the axis of the micro (Hygrophorus Russo-coriaceus), that it is rare; but scope the appearance is totally changed, and the I have a suspicion that it may have been overlooked wedge-shaped markings, which I believe to be as the young, or a small state of Hygrophorus virhollows between the pleats or corrugations and gincus, which at a distance it somewhat resembles. not particles, as stated in the “Micrographic It may, however, be readily known from that species Dictionary” and elsewhere), come into view directly. by its delightful scent alone, which it retains after Their dark outlines, I think, represent the shelv- drying, and to such an extent, that I think it might ing sides of the little pits, and the bright space in be made available for the scenting of drawers, &c. the centre of each is the deepest portion, which In the same pasture I gathered Hygrophorus from its position with regard to the ray, obstructs murinaceus, which possesses the odour of aquafortis the least amount of light.
-far less agreeable, but perhaps equally remark· By moving the diaphragms of Powell's condenser able. The collector of the larger fungi is frea little backwards and forwards, so as to obtain quently reminded of this singular similarity of odour alternately direct and oblique light, the appearances to a series of odd things, both of a disgusting and represented in the figure attached are given. The agreeable nature, as the following brief enumeraconclusion I have arrived at seems still further tion will illustrate, viz., cinnamon, garlic, heliosupported, if one of the most strongly-marked scales trope, cucumber, gas-tar, tarragon, new flour, mice, be examined with a žth objective, and Smith and bugs, ripe apricot, putrid flesh, &c. The similarity Beck's patent illuminator for opaque objects under of form and colour which some insects bear to high powers. The wedge-shaped markings are then portions of the vegetable kingdom, would lead one distinctly seen to be little pits.
to suppose that they were designed to protect them Opaque illumination by means of the side-con- from wholesale destruction by birds, &c.; but as densing lens and a sth object-glass shows the tops of regards the odour of fungi, it seems more difficult the ridges of pleats illuminated, and the spaces to form an opinion. The mycologist, however, between in very strong shadow, provided the beam often finds that they serve him as valuable aids in of light strike the scale sideways. If it strike the determination of species, and without which, lengthways, the view is too indistinct to be satis his conclusions might be more exposed to error. factory. My opinion on the subject differs slightly
H. BEACH. from that of Mr. Beck, who regards the wedgeshaped markings as elevations, and argues ac MARKS.-A delta is a water-mark; a round crater cordingly. The question as to whether they are a fire-mark; and every force which acts on a surhollows or elevations is of no great importance, and face makes a tool-mark which may be learned. Each it is exceedingly difficult of resolution. Mr. Beck's mark is like a letter. It has a form and a meaning, remarks refer to the test scale.
but only for those who learn to read.-Frost and S. J. MCINTIRE. | Fire.
THE WASP'S STING, ITS POISON GLAND.
SPIROGYRA. THE discussion relative to the fang and poison THE various species of Spirogyra are found,
1 gland of the spider, which has appeared, from I during the spring and summer, in open time to time, in the pages of SCIENCE-GOSSIP, and
exposed pools of water, or in slowly moving streams, in which I have taken a part, has led me to examine and are all remarkable for the beautiful manner in the stings of bees and wasps, with a view to satisfy
which the bands of chlorophyll are disposed within myself as to their structure, and to observe what
the cells. They consist of bright green filaments, similarity there might be between them and the varying from the hundredth part of an inch to a fangs of spiders, especially in reference to their yard in length, made up of cylindrical cells, joined poison glands. Accordingly, I cut out the sting of end to end. Some of these occur in nearly every a wasp with all its attachments, in as unbroken a pool, and appear on the top of the water in green state as possible. I spread out the whole on a
or brownish patches, with bubbles of air entangled glass slide, and washed the parts with lukewarm in their mass. In streams, they attach themselves water, without using liquor potassæ. I then to weeds, and the long green filaments, waved to allowed the water to evaporate gradually, and the and fro by the current, are very pretty. sting, &c., to become quite dry on the slide; and When viewed under the microscope, with a power finally, having moistened the object with turpentine,
of one or two hundred diameters, the bands of I mounted it in balsam.
chlorophyll are seen disposed in various elegant I found that in wasps, as in spiders (SCIENCE spirals. In some species these bands are single, Gossip, for 1866, page 229), the poison gland is
in others there are two, three, or four. Upon these attached by a hollow cord of about the length of
bands, which are generally slightly jagged along the gland itself, and that the course of the cord their edges, are grains of brighter green, disposed could be traced down the body of the sting. The
at pretty regular intervals, and adding greatly to gland is similar in shape and size to that of the
the beauty of the plant. Sometimes the larger spider, and when examined under the microscope, grains are surrounded with smaller ones, and the with ordinary transmitted light, did not exhibit
bands appear like two festoons of exquisite green anything remarkable, except that there was a kind
flowers (fig. 3). of knot in its extreme end, and attached to it,
In some cells, but by no means in all, a nucleus which seemed to be ramified with a structure of
may be seen, clinging to the side of the cell or tracheæ. Upon examination with polarized light,
apparently held in its position by strings of protonothing particular demanded attention, until this plasm (figs. 1, 5). In the terminal cell the rotation knot came in the field of view, when brilliant star
| of the protoplasm is frequently observable, the like crystals blazed forth on the dark ground. The
current seeming to flow down the middle of the cell, crystals were small, each had a dark cross in its
and return by the sides. centre, and with selenite gave the usual appearance A young plant is represented in fig. 6, the whole of complementary colours.
number of cells in which was 20, but only those at If I would indulge in a deduction from the above each end and in the middle are represented, in appearances, I would say, that the gland contained
order to show the root-like termination, and the a fluid poison, in which the crystals were in solution,
manner in which the spiral bands are gradually the evaporation of the fluid poison leaving the developed. In the two lowest cells the chlorophyll crystals as observed.
appears in a shapeless mass, in the third, the spiral It would be interesting to try whether a similar
bands begin to be marked, and in the middle of the treatment of the poison glands of the spider would
filament they appear as at b. At the growing lead to similar results. This I may attend to, on a point, they are distinctly marked, but somewhat future occasion, if I be not anticipated by a more
compressed. In the ordinary cells of this specics, diligent observer.
the spiral bands, which are rather lax at the ends The slide containing the sting and the gland with
of the cell, in the middle run close up to one the crystals, I have in my possession, and I have no
another, and give a peculiar character to the objection to lend it for the examination of any reader
filament. of SCIENCE-GOSSIP, who may be sceptical, because The cells of different species are not always terunable to verify the appearances I have related.
minated in the same manner. In some a cell sepaArmagh. Lewis G. MILLS, LL.B. / rated from the rest exhibits a rounded outline, in
others it is at first slightly constricted, and then A LANDSMAN who has only seen a puddle in a rounded (fig. 10). In the former case, the junction storm, has no clear notion of the Atlantic in a gale; of two cells is flat, but in the latter the cell-wall is and so it is with a man who has never been far from folded back. This may be readily observed, when home.-J. F. Campbell.
the plant is treated with iodine (fig. 10,5).
All the species of Spirogyra exhibit the process of and the contents of one cell pass into the other. conjugation. Two neighbouring plants throw out Before, however, this takes place, the spiral coils from the sides of their cells little processes (figs. 7, are relaxed, and their curves turned towards the 8); when these meet together a union is effected, process; then the contents lose their symmetrical the intervening cell-walls are absorbed, or ruptured, I form, and become altogether shapeless (figs. 7, 9).