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—Is there any distinguishable feature in the male young of kites, ravens, or magpies at an early age, so that anyone wishing to rear a male bird might be able to select one without rearing the whole nestlings for the plumage to determine? If the males can be scientifically defined, it would save a deal of trouble to many.—Ross.

—We have received several communications, but do not think it prudent to occupy more space with this subject; especially as they contain no facts which have not already been published in "The Zoologist," p. 6,983 and Gosse's "Romance of Natural History."—''Ed. Sc. G.''

—Our correspondent says that in rubbing down sections of the spines, by whatever mode it is done, the numerous cells accumulate foreign matters to a considerable extent, and that no one has yet suggested a method by which these sections can be made perfectly clean. Methods applicable to bone and other equally hard substances, are not necessarily successful in this instance.

—(In reply to Mrs. D.) The fossil forwarded for identification, obtained from the railway-cutting near Evesham, is Rhynchonella tetrahedra, Sowerby, one of the most characteristic fossils of the zone of Ammonites margitatus, or the marlstone of the middle lias.—

—Can you or any of your readers inform me whether toads inhabit London houses? To-day, March 8th, my servant found a full-sized toad in an underground and somewhat damp apartment of my house; and he informs me that he found a smaller one in the same place some months ago. If the toad is an indigenous citizen, on what does he subsist? Is he in any way injurious? Where are the ova deposited?—

—(In reply to )—Garnets occur abundantly in mica slate, hornblende, slate, and gneiss; somewhat less frequently in granite and granular limestone; sometimes in serpentine and lava.

—Can you, or any of your readers, explain to me why it is that if a frond of fern is placed in mould for the purpose of rearing seedlings, the young plants produced are not invariably of the same description as the parent frond. Such is my experience, and that of other fern-fanciers who have spoken to me on the subject.—

—In last October I examined some specimens of the Cosmarium, and was rather surprised to observe a brisk movement of particles going on between the two lobes of the plant, very similar to the circulation in the ends of Closterium lunata, only the movement seemed quicker, and the particles much more numerous and a little larger. I referred to "Carpenter," and other books on Microscopy, but have not yet found anything about any movement seen in the Cosmarium. I have often seen this since, and in all cases the endochrome has been contracted towards the centre of the lobes, leaving a transparent space between them, in which the circulation took place. I shall be glad to hear whether this has been seen before, or if I may claim the honour of this discovery.— Holland.—[Our correspondent should have referred to the "Micrographical Dictionary," p. 186, and read as follows:—"A peculiar swarming motion is observable at times in the cell contents of this genus, different from the circulation in Closterium."—''Ed. Sc. G.'']

—I bought at Covent Garden market a short time since a piece of imitation rock-work made of cinders. I noticed each piece was joined together with a black cement. Can you, or any of your obliging correspondents, tell me how it is made, or where it can be purchased?—Leicester.

—It is a common custom in the north of Ireland for farmers, whose holdings do not admit of their keeping two horses, to mutually assist by lending to each other alternately, one having the use of his own and his neighbour's horse on one day, while his neighbour has both on the next. If, before leaving home, one farmer gives his horse a feed of whins (Ulex Europæus), which when pounded or beaten is a common article of fodder, while when pounded or beaten is a common article of fodder, while the other feeds his horse on hay or oats, when the horses are put into the plough, the one that has been fed on the hay or corn becomes quite sick, and only recovers when his fellow is removed from him, or the effects of his meal pass off. Can any of your readers offer any explanation of this fact?—R.

—In reply to a correspondent, as to the possibility of preparing specimens of the fresh-water polyzoa, or indeed any of the marine zoophytes, with the tentacula expanded, as permanent objects for the microscope, I have found the following method, though not uniformly satisfactory, being sometimes rather uncertain in its results; yet with patience, and by operating upon a number of slides at the same time, may give, in six cases out of twelve, all that can be desired. First, of the fresh-water species, say Lophopus; a portion should be placed in a cell—I prefer those formed by grinding out a basin in the slip of glass with a drop of water, and covered with thin glass; in a few minutes this magnificent creature will expand its glorious horseshoe-shaped head of tentacula, quivering with ciliary action; then, while it is under the microscope, allow a drop of pure alcohol to run under the cover into the cell; it instantly causes death, and generally with the tentacula extended; in many cases excessively so. The cell can then be cemented with Brunswick black. But the greater certainty of success is with the marine species, in consequence of the support given by the polypidom. Coryne, for instance, treated with alcohol while in a living state, as I have described, makes a beautiful permanent object, and illuminated with a parabaloid or spotted lens, scarcely inferior to when in its living state. Entromostraca, mounted with alcohol in a similar way, scarcely ever fail.—, Crouch End.

—"Dytiscus Marginalis" should tempt his pet friend with a fine fat slug. I think it very liekly that he finds food to his taste in the moss with which his prison-house is filled, and that he has not absolutely fasted for six months. Insects and slugs are possibly in the habit of visiting the moss-cup. Indeed, I should not be at all astonished to hear that he has been sleeping half the time, after the fashion of some of his order, the Bufoidæ family. Tritons have, I understand, a trick of swallowing their own skin; perchance Mr. Salamander has dined on his cast-off suit of clothes, and found them indigestible; or may be he took a fancy to a few young relatives in their tadpole state, and, repenting himself of such a cannibalish trick, is now fasting by way of penance. Aquatic insects and larvæ are his natural food, but I think he indulges in the freaks above described at times.—