which the children of Israel were fed, there is really little inconsistent with the Scriptural account; allowing that the manna was miraculously supplied, it might still be brought about by natural agency, for Mr. Berkeley further mentions that, lying loose on the ground, without any attachment, it is easily rolled along by the wind, and sometimes piled together in strata several inches in thickness. Nay, more, it is still, occasionally rained from heaven, being carrid up by whirlwinds, and after traversing the air for many miles, falls precisely as the showers of fish, frogs, and gnats' larvæ, which afford sensational paragraphs for our own newspapers. Such a shower of these lichens fell about twenty years ago at Erzeroum, during a time of great scarcity; this bread from heaven affording opportune relief to the inhabitants. Probably, as Mr. Munby suggests, when gathered alive and placed in a heap, it would in such a climate soon ferment, and then "breed worms and stink;" the injunction to gather it daily might therefore have a sanitary import, and as a double quantity was collected on the day preceding the sabbath, little would be found on that day; but the Biblical narrative tells us, that which remained over on the sabbath "did not stink." The characters also of the manna do not accord in all points,-" as small as hoar frost on the ground-it was like coriander seed, white, and the taste like wafers made with honey."

Whether the manna of the wilderness was or was not a natural product is fully discussed in the Dictionary of the Bible (published by Murray in 1863, and the work of sixty-seven of the most eminent divines); from which it would appear to have been always considered an open question; Lichen esculentus, Pallas, does not, however, seem to have been known to them, or it would no doubt have been noticed, and also the peculiarity that it may be gathered all the year round.

the

R. BRAITHWAITE.

VARIOUS FORMS OF POLLEN-GRAINS.

each tiny grain presented, and the beauteous symmetry of their varied markings. I was so pleased at the end of my research that I determined next day to get a fresh supply of the same flowers and sketch their uncommon pollen-grains. This I accordingly did, and now enclose sketches of the same, giving them their common as well as botanical names.

Fig. 44. Pollen of Bladder Campion, Broad-leaved Helleborine, and Scabiosa arvensis.

The objects were principally magnified with a halfinch objective, and some few of the larger ones with an inch power and A eyepiece. I feel sure these curiously-shaped pollen will be interesting to many

Fig. 45. Pollen of Potamogeton densum, Sanguisorba officinalis, and Eye-bright.

of your botanical readers. I think, however, as I am writing on this subject, it will not be out of place if I give a brief sketch of the function of the pollen of a flower, and the part it takes in the economy

Fig. 46. Follen of Cnicus lanceolatus, Jucundus conglomeratus, and Orobus tuberosus.

of the plant creation. The pollen has the peculiar power of fructifying each seed which is growing in the ovary of the plant; the anthers contain the

when getting over a wall, I was surprised

to see my boots changed from black to a golden tinge; naturally I felt inquisitive to learn what this proceeded from. On examining them closer with my Coddington lens, I found that the beautiful yellow colour proceeded from an accumulation of the pollen of the various wild flowers which were then in bloom. I gathered about a dozen flowers of the different wild plants that grew around where I was standing. When evening came I amused myself by subjecting the pollen of them to an investigation under my microscope; it was amazing to see the numerous forms

Fig. 47. Pollen of Hieracium subaudum, Erica ciliaris, and Mentha viridis.

full bloom, the pistil, then fully developed, has on the surface of its stigma a viscid fluid, which makes the pollen adhere to it. When the anther has reached its zenith, the pollen falls off into a channel, which conveys it into the ovary underneath. There are

many cells in the tiny pollen-grain, and a fluid called fovilla, which gives the creative power to the ovule.. As soon as the pollen falls on the stigma it sends forth a tube, long or short, as the case may be; this descends through the style, enters the ovary, reaches the ovule, pouring in the fovilla, which gives life to the future plant, which it preserves and nourishes. in the seed. The quantity of pollen in a plant is astonishing; but when it is recollected the numberless insects which feed on it, it can then be understood that an all-wise Creator has made provision for the different vicissitudes of the vegetable kingdom. In conclusion, my reason for selecting the pollen of wild flowers instead of cultivated ones, was, that there are many persons who have not access to flower-gardens, especially those who live in towns, and hence cannot investigate the subject for themselves; whereas, in the wide garden of nature, all can easily go into the green fields and gather the various flowers they care for, and by an examination of their varied pollen-grain, can gain both information and pleasure at a very small expense, granting, of course, that they possess a microscope of moderate magnifying power. The pollen-grains look charming when illuminated with a parabolic reflector, which throws them out in bold relief from the black background. Pollen-grains are very easily mounted by shaking the grains off on a piece of black paper and drying them carefully; then mount them in a shallow cell, on black paper, as an opaque object-the larger kind are the best for this purpose, such as the Mallow, Hollyhock, &c.; some of the darker-coloured pollen can very well be mounted in balsam. This operation requires to be carefully done, as the pollen, being soft, can be seriously injured by over-pressure. Having many of these specimens in my collection, I can well testify that they are highly interesting, even to those who have little interest in the subject, but still admire them, on account of their eccentricity of form. RALPH H. WESTROPP, A.B., T.C.D.

MICROSCOPY.

ARBORESCENT SLIDES.-If a few drops of the solution of nitrate of silver be placed in a clean copper cell cemented upon a glass slide, the growth of crystals of metallic silver will immediately start from the margin of the inclosed space and proceed with great regularity towards the centre. Crystals of the newly-formed compound, nitrate of copper, will be deposited upon the surface of the silver as the water evaporates, but by carefully immersing the slide in clean water these will be redissolved, and thus easily got rid of; when thus washed, the arborescent silver may be mounted either dry or in fluid, without in any way injuring or disturbing it, as will almost invariably be the case when it is precipitated upon a wire, as recommended by your

correspondents in SCIENCE-GOSSIP, pp. 17 and 47. Slides of arborescent lead may be prepared in the same way from a solution of acetate of lead in a zinc cell (or by "F. K.'s" plan with a small shred of zinc). The similarity between the crystals of silver and lead has frequently been remarked, and it will be remembered that in nature these metals are constantly found in combination. Arborescent silver may also be prepared in great perfection by decomposing a solution of the nitrate by means of a weak galvanic current. The terminal wires in this case should be of platinum, and may be conveniently brought upon the stage of the microscope through two pieces of small glass tube mounted in the same way as the stage forceps: they both hold and insulate the wires and admit of movement in any required direction. A commutator-or contrivance for breaking or reversing the current-introduced between the platinum terminals and the battery will add very greatly to the interest of the experiment; a cell or trough containing the solution should then be placed upon the stage and the ends of the platinum wires immersed in it. On making the connection with the battery an exquisitely beautiful growth of silver fern-like crystals will immediately take place upon the wire connected with the positive plate, a simultaneous growth of prismatic crystals starting from the opposite wire, On breaking the current the growth will instantly cease, and on reversing it the curious effect of the disappearance of the crystals in the inverse order of their growth will be seen until all have been redissolved, when a fresh growth will immediately commence upon the opposite wires; and this alternate growth and un-growth may be repeated any number of times by a careful experimenter, to whom details as to illumination, magnifying power, &c., will be unnecessary here. It is, however, important to mention that only a weak current should be employed, as otherwise the process goes on too rapidly for convenient observation, and bubbles of gas are apt to be disengaged from the wires, which, in addition to disturbing the general tranquillity of the fluid, will be sure to detach the crystals themselves. A single cell of the smallest size "Leclanché" battery, or one of "Walker's" containing very diluted acid, will be found amply sufficient for the purpose. The foregoing experiment was detailed in the course of a paper read by the writer at one of the early meetings of the Quekett Club, but may yet be interesting to some readers of SCIENCE-GOSSIP, seeing that the subject has recently been revived in its pages.—R. T. L..

MALTWOOD'S FINDER.-This little instrument, so well known to microscopists, has perhaps not been so generally adopted as it deserves to be. This has arisen from two causes, the first being the somewhat cumbrous method of registration usually

of

adopted, and, secondly, from difficulty of finding an object registered by different observers and "finders," arising from slight errors in the Finder itself, and also from the various methods registration adopted by different observers. Mr. W. K. Bridgeman, president of the Norfolk and Norwich Microscopical Society, has suggested a plan which, by the aid of a very simple piece of apparatus, obviates, to a very considerable extent, the above-named objections to the Finder. He inserts in the eyepiece over the diaphragm an "indicator." This can be made in the following manner: Unscrew the top of the eyepiece, so as to expose the diaphragm; cut a piece of card to fit firmly over it; draw a line across the diameter of the disk of card, and cut an aperture in it of the same size as that in the diaphragm; cut a little notch in the ring in the same direction as the line, and gum a fine bristle in it, the point reaching nearly to the centre; when dry, place in the eyepiece (close to the diaphragm) and screw in the eye lens, and the indicator is ready for use. Finders are only necessary when the object is minute, or very rare on the slide, and the higher powers are used. One of the squares in Maltwood's finder usually fills the whole of the field of a objective; and if it so happened that an object always occupied the same position as a square, no great difficulty would be found in the registration of its position; but it more frequently occurs that portions of squares only are in the field; as for example,2 1/1 When this is the case, the indi11 12 cator will be found of the greatest use. Bring the object to be registered close to the point of the bristle, remove the slide, and put the finder in its place, and note the exact position of the point. We will suppose that the figures are

1

2

or

1

or

I' the dot representing the point of the indicator; the position of the object must then be registered thus: 1., the dot always representing

25 25

the exact position of the object when in the centre of the field. The rule for notation is that the square on which the pointer rests is that which must be written down. The error existing between two finders may be detected and remedied in the following manner: Place the finder on the stage, and bring the centre square into view, which would appear thus: ; remove it and put an ordinary glass slide in its place; make a small perforation in a gummed label; moisten it, and slip it on the slide, so that the aperture is central. The slide thus prepared can then be sent with the slides requiring examination; the second observer will then test his own finder by the slide, and the error, if any, noted. I have tried the plan proposed by Mr. Bridgeman, and find that it answers admirably.

One or two slight improvements may perhaps be made-a ring of thin brass might be substituted for card, and a small brass pin soldered into it for the purpose of removing it from the eyepiece when required, and in place of the bristle, a piece of fine spun glass will be found preferable; indeed, so slight a portion of the field is occupied by it, that the indicator may always remain in the eyepiece, and will be found useful in calling another observer's attention to any object, or part of an object, that may be desired. The test slide may be made a more permanent record by marking the centre with a small ink-dot, and when dry, ruling (with a diamond) two lines at right angles to each other across the dot; the point of intersection will then be found in the centre of the field.-F. Kitton.

A NEW GONIOMETER EYEPIECE.-Dr. Porter and Mr. J. P. Southworth have succeeded in making an eyepiece micro neter and goniometer, which they say, equal in cheapness and accuracy, and are much cheaper, than any yet seen. The objection to the eyepiece micrometer in use is the lack of boldness in the division lines, which makes them faint, and hurtful to the eyes. To overcome this objection, they have been led to make micrometers by the aid of photography, and have succeeded. The advantages of their goniometers over that ordinarily in use, is, that the angles of the crystal and the degrees of the goniometer are on the same line of sight within the tube of the microscope, while in the ordinary goniometer the degrees are marked outside the tube. The photographic processes by means of which this is achieved are not new, but may be learned in any work on that subject.

BOTANY.

RANUNCULUS FICARIA, L.-A common name for this species sometimes met with in our Floras is "Lesser Celandine." This is a deceptive and confusing name; it is really a corruption of Chelidonium, and the name of celandine should with propriety only be applied to Chelidonium majus. The true English name for this plant is Pilewort. Every one who observes the "little things of nature" must have noticed the peculiar whitening of the glossy golden petals after they have been fully expanded about fourteen days. Sometimes they appear with only white patches in different parts of the petals; at others, it commences at the tip, and runs half or two-thirds down the petals. Underneath the white patch appears as if the cellular matter was in a state of decay. The corolla is not marcescent, as in the Campanulas (Bellflowers). The term marcescent cannot be applied to a deciduous corolla, and without doubt the petals of the Pilewort are deciduous. I am not aware that any satisfactory

reason has been assigned for this peculiar phenomenon, which does not exist only in this species, but may be seen in several buttercups. The changes going on in the petals of the Alkanet, Evening Primrose, &c., are different to the Pilewort. In the Evening Primrose the corolla does not suffer the loss of colour; it is only more intense, as from light yellow often to bright pink, or purple; on the contrary, the Alkanet changes from blue to pink. May not the following be assigned as one reason for this change?-at all events it is in harmony with first principles. At the season when the Pilewort begins to bloom, very few flowers are to be met with. The brilliant petals may then be designed to attract the honey-bee, so as to bring about more effectually the fertilization of the ovules: this being a accomplished, the corolla begins at once to exhibit the white blotches. After the whitened and withered-looking petals appear, the bee never visits the flower. I speak now from my own limited observation, which may not be in strict accordance with the observations of other botanists. The carpels are but loosely placed on the receptacle, and are easily displaced. If they fall before they are fully matured, of course germination cannot take place thus the speckled petals may be produced solely to repel bees and other insects. The petals vary much, both in number and size; this may depend to a great extent on the richness or fertility of the soil in which they are growing. The R. ficaria of Linnæus is now divided into two very distinct varieties, recognized chiefly by the variation in the leaf (see Syme's "English Botany "). The botanical reader will do well to keep a lookout this spring, as their distribution does not seem to be well ascertained. The one named R. divergens, F. Schultz, appears the most frequent; whereas, so far as I am informed, the R. incumbens is rare in our northern counties.-James F. Robinson.

:

ABNORMAL ERICAS.-Mr. Britten draws attention, in the Journal of Botany, to an anandro us variety of Erica cinerea, from Wiltshire, which has year after year brought forth similar blossoms. Their appearance is very remarkable, and due to the fact that both corolla and stamens were wanting. The specimens are interesting on account of their apparent permanence.

HYMENOPHYLLUM TUNBRIDGENSE.-I beg to say that I know a locality for this fern not far from Llanberis. It grows, in company with H. Wilsoni, in a somewhat dangerous 'place, but was procured for me by a native about eighteen months ago.R. M. Middleton.

BELFAST NATURALISTS' FIELD CLUB.-The eighth annual report of this flourishing club has just been issued. Among other interesting material there are given several localities for some of the more in

teresting plants of the district; among others,Carex strigosa, C. districha, Arenaria trinervis, Tortula recurviflora, Orthotrichum leiocarpum, and many others, some of which have not been before recorded.

THE FLORA OF Berkshire.—Mr. James Britten, of the British Museum, has just published what he modestly terms "Contributions" to the flora of the above county, but which is a most valuable summary of the botanical knowledge of that part of England. It takes the form of a list, showing how much is known, and how much more remains to be known, of the distribution of the species found within its limits. Altogether the enumeration of the species may be looked upon as a record of the plants known to exist in Berkshire in, or previously to, 1871. The county has been divided into five districts, for the purposes of floral distribution. The authorities quoted, from old Gerarde downwards, are very numerous, and Mr. Britten may be congratulated for having successfully accomplished a very difficult and onerous task. The list contains no fewer than 844 species.

MOSSES OF THE LONDON DISTRICT.-Mr. T. Howse asks in the January number of SCIENCEGOSSIP for habitats of mosses near London. The following list contains some that I found while residing in London five or six years ago. In communicating them, I must express the hope that the rapacity of collectors will not exterminate those that the inevitable encroachments of bricks and mortar have hitherto spared. I would reccommend collectors to explore Hampstead Heath well, especially a bog in the farther part; also the banks and walls bordering the road from Hampstead to Highgate. A walk from Mill Hill through the lanes by Shenley to St. Albans also yielded me many species. Another good day's walk was from Barnes Common (where many rare plants are to be found) up the lane leading to Roehampton; thence across Wimbledon Common to Combe Wood: Sphagnum acutifolium, Hampstead Heath; S. cymbifolium, Wimbledon; S. squarrosum, Walthamstow; Phascum subulatum, Stanmore Heath; Weissia controversa, banks of road from Hampstead to Highgate; W. cirrhata, on old paling in lane from Barnes Common to Roehampton; Dicranum scoparium, Hampstead; D. heteromallum, Clapham Common; Pottia truncata, Old Oak Common; Didymodon rubellus, Highgate; Tortula muralis, Kilburn; T. subuluta, Elstree; Atrichum undulatum, Combe Wood, Shenley; Pogonatum nanum, Hampstead Heath; Polytrichum commune, Barnes and Wimbledon Commons; P. juniperinum, Barnes Common; Aulacomnium palustre, Hampstead and Roehampton; A. androgynum, Barnes and St. Albans; Bryum nutans, Wimbledon Common; B. capillare, Mitcham ; B. argenteum, Kilburn; Mnium hornum, Highgate; Funaria hygro

metrica, Paddington goods - station; Fissidens bryoides, Hampstead, near Finchley Road; F. taxifolius,Colney Street; Hypnum confertum, St. Albans ; H. rutabulum, Kensal Green and Highgate; H. prælongum, Hampstead; H. striatum, H. tamariscinum, H. splendens, Shenley; H. cuspidatum, Roehampton; H. fluitans, Kensal Green and Hampstead; H. compressiforme, St. Albans; H. denticulatum, Highgate; Scapania undulata, Hampstead; Jungermannia inflata, Wimbledon; Lophocolea bidentata, Shenley.-H. Franklin Parsons, M.D.

ZOOLOGY.

THE CRYSTAL PALACE AQUARIUM.-A capital guide-book to the Crystal Palace Aquarium has just appeared, written by Mr. W. A. Lloyd, the superintendent of the aquarium. The great interest in natural history which this beautifullyfitted-up aquarium has already elicited will be intelligently ministered to by this little handbook. It contains a brief history of aquarium-building, and a detailed explanation of the principles upon which that at the Crystal Palace is constructed. Then follows the natural history of the various animals living in the several tanks, with such original notes of their habits, &c., as have been studied since they were placed in their new house.

THE GREAT AUK.—Dr. Hayes, in his work on Arctic travel, just published, records a visit to Greenland, and, speaking of Mr. Hansen, a naturalist there, says :-"To the study of the birds of the region and their habits he has devoted much attention. The Great Auk, long since supposed to be extinct, he told us had recently been seen on one of the Whale-fish islands. Two years before one had actually been captured by a native, who, being hungry, and wholly ignorant of the great value of the prize he had secured, proceeded at once to eat it, much to the disgust of Mr. Hansen, who did not learn of it until too late to come to the rescue. Mr. Hansen was at this time Governor of Godhavn, Disco Island, and had previously been Governor of Proven and Upernavik."

MUSICAL MICE.-As this subject has been discussed in our columns lately, it will not be out of place to draw attention to an article in the American Naturalist, in which Dr. Lockwood gives a description of a singing vesper-mouse (Hesperomys). The mouse in question was brought from Florida, and, at first, the twitterings were ascribed to swallows. One day the mouse came on the hearth, sat up, and sung for a minute or so, and then retired. Eventually it fell into Dr. Lockwood's hands, so that he could minutely study its habits. It was at night that its song usually began, and so distinct were its notes that Dr. Lockwood had them written down, and they are given in the article to which we are now

referring. The notation in some parts much resembles that of the nightingale, only that it is in a different key. The scope of the notes was remarkable, falling an octave with all the precision possible. The mouse would burst into song, like a bird, all on a sudden. One song, named and written down by Dr. Lockwood as the "Grand Rôle," was singular for its strange diversity of changes. So soft and silvery were the notes, that the author remarks that if they had been uttered by a canary the bird would have been worth a hundred dollars! This singing would sometimes last as long as nine minutes. The doctor is utterly opposed to the idea that this singing was due to bronchial disease, and gives undoubted reasons for his belief; amongst others, that most of the notes uttered were those it would have been most impossible to have sounded under any form of bronchial affection.

PIKE-FISHING IN NORFOLK.-Norfolk is the Paradise of the Pike. We may read in the newspapers of his growing to an enormous size in some solitary fishpond, where, for aught we know, he may have reigned supreme since the days when the preElizabethan monks placed him there as a young pikerel. But nowhere does the average size of pike equal their condition in the Norfolk rivers and broads. There you find them in all ages and sizes from the three-inch jack just trying his "prentis han"" on equally juvenile roach and dace, to the still growing, elderly individuals over three feet long. Their number is legion; and Norfolk pike-fishing, in my estimation, beats both trout- and salmon fishing for right-down good sport. If you are inclined to be sentimental, and to subscribe to Mr. Freeman's views about hunting, you have the satisfaction of knowing, when pike-fishing, that you have not lured poor herbivorous creatures to their destruction, but simply caught the carnivorous cannibal that intended to do unto others what you intend to do to him!-J. E. Taylor, in "Belgravia."

THE BUTTERFLIES OF THE CHANNEL ISLES.-As these islands are a very favourite resort of tourists and naturalists during the summer months, it may not be uninteresting to the readers of SCIENCEGOSSIP to hear what my experience has been, and I am the more induced to send these notes for insertion in your excellent Magazine because it was not until the end of a long stay in Jersey that I caught anything worth mentioning. In this island it is only the south-east district which contains rare Lepidoptera. Between the hills and the sea I found C. edusa in profusion; C. hyale came flitting by now and then, and the rare P. daplidice was not uncommon at midday. In the lucern-fields I found A. lathonia; but this latter insect was very hard to catch. The specimens of C. edusa which I caught showed a decided richness and depth of colour which the English specimens do not possess. In fact, on