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HARDWICKE'S SCIENCE-GOSSIP. 



he cornmeiiced barking furiously, frying with his 

 paws to knock it down, which, if on the lower panes, 

 he generally succeeded in doing ; but the curious 

 part was, that as soon as the insect was on the 

 ground, the dog began turning it over and over 

 with his tongue for about ten minutes, all the 

 time making a peculiar hissing noise, dragging it 

 sometimes half across the room, and eventually eat- 

 ing it with the greatest relish, but apparently un- 

 conscious of the danger of the sting if eaten imme- 

 diately after death ; but if he could pounce on one 

 in the act of flying, he swallowed it at once with 

 impunity, evidently regarding it as a bonne-bouche, 

 from the frantic manner in which he pursued any 

 that came in his way. — *S T . M. P. 



White Varnish eor Microscopic Cells. — I 

 should not advise " W. G. C." nor any amateur to 

 trouble themselves with making their own varnishes, 

 as dealers in microscopic material can supply them 

 ready for work at nearly the price the material 

 would cost an amateur. — T. McG. 



Tadpoles, &c— In reply to A. F. Maingay, allow 

 me to say, that in my article ou tadpoles of newts, &c, 

 the seventh line from the end, the vrovd frog ought to 

 be substituted instead of newt. It then reads as 

 follows : — " The tadpole of the frog has gills, and a 

 tail during part of its life . . . the tadpole of the 

 newt has the tail permanently" &c. — //. E. Forrest. 



"Mocha Stones" are so called, because 

 found in abundance at Mocha, in Arabia. They 

 are found in Amygdaloidal Trap, which appears 

 to have been originally vesicular lavas, through 

 which waters charged with siliceous and calcareous 

 solutions had percolated for ages until they finally 

 filled up the cavities with agates, &c. The dendritic 

 markings are metallic, not fossil vegetation, to which 

 they bear a resemblance. It is needless to say that 

 these igneous rocks are a very old formation. The 

 varieties of agate, onyx, carnelian, jasper, &c, which 

 are so abundant on the beach at Aberystwith, most 

 probably come from some trap rocks on the north 

 side of the bay. The metal in the transparent 

 agate or chalcedony is mostly iron, which gives 

 the colours, dark green, yellow, and reddish brown, 

 seen in the Mocha, and the green and brown moss 

 agate— H. C. E. 



Mocha Stones.— I send the following extract 

 from Sowerby's "Popular Mineralogy": — "On 

 this subject Phillips observes, — ' Dr. McCulloch has 

 instituted a very ingenious inquiry into the nature 

 of those vegetable appearances of different colours 

 visible in the more transparent chalcedonies, which 

 are termed Mocha, and more particularly in those 

 which are less so, termed Agate. Close observation, 

 added to chemical experience, induces the conclusion 

 that many of these appearances are owing to the 

 existence in the stone of aquatic confervse ; that 

 these plants sometimes appear perfectly in their 

 natural form and colour ; iu others they seem to be 

 coated by oxide of iron, which occasionally hides the 

 form of the plant, and discolours it. Mosses and 

 some varieties of lichen have been observed, and 

 occasionally chlorite, which sometimes is so disposed 

 as to represent a vegetable. A chrysalis, probably 

 of a moth (?), was observed in an onyx-agate in a 

 ring in the possession of Earl Powis.' Against the 

 experience of Dr. McCulloch we should be sorry to 

 offer an opinion, but we think the subject requires 

 further investigation. Mocha stone is a most beau- 

 tiful, valuable agate, consisting of white cornelian, 



with patches here and there of a deep brown colour 

 and dentritic appearance. It derives its name 

 from Mocha, in Arabia, whence it is brought." 

 With regard to the Mocha being found at Aberyst-. 

 with, I am afraid that it is only in the shops that it 

 will be met with; large quantities of pebbles are 

 imported from Germany (some with colouring 

 matter, especially blue, infused into them), and 

 when stones are brought from the shore to the 

 lapidary to be cut and polished, they are frequently 

 thrown away, and the foreign ones already prepared 

 are returned to the happy tinders. There are beau- 

 tiful specimens of Indian green moss agates sold at 

 Aberystwith, and people are told that they are 

 found upon the beach there, but only in the winter 

 months, when visitors are scarce, either being of a 

 shy nature, or of migratory habits, like the fieldfare, 

 &C.—E. M. 



On collecting Hymenopteea, &c. — Some of 

 your correspondents encumber ihemselves with more 

 bottles, tins, and boxes than there is any necessity 

 for; the simplest, most efficient, and least expensive 

 plan is the following : — Laurel-leaves, as Mr. 

 Blackett states, are the best,_ gathered in spring, 

 but not too young, if pounded in a mortar, instead of 

 cut up merely. A good-sized bottle of the bruised 

 leaves will be good for killing Coleoptera, Hymeno- 

 ptera ; in fact, all insect life during the year. I use 

 miuenowin December which were gathered last June. 

 The most convenient collecting-bottle is anordinary 

 two-ounce or four-ounce wide-mouth, with turned- 

 back rim, and tight-fitting cork. In the centre of 

 the cork pierce with a borer a hole, in which a 

 glass tube will fit, open at both ends._ I use a 

 one-drachm tube bottle, the bottom of which I cut off 

 by notching with a file, applying a red-hot ring of 

 wire, and drop a little water over it : this cracks it 

 round tolerably straight. Hold the edge in a gas 

 flame for a few seconds to melt off the sharp edge, 

 tie a piece of muslin round the bottom, and cork the 

 mouth; fit this tube tightly into the cork of the 

 larger bottle, which fill half or three parts full of 

 bruised leaves. This forms a cheap and convenient 

 double bottle. The larger insects are easily put 

 into the large bottle, while the tube is kept for the 

 smaller or any rare species. They are killed in a 

 few seconds, and will keep in capital condition for 

 setting for some weeks, or even months if needed. 

 It is well, however, not to keep them too long. 

 With this single bottle, I think, all a collector's 

 requirements are met. Chloroform, cyanide of 

 potassium, sulphur, and ammonia are all nuisances, 

 and can be very advantageously dispensed with. — 

 E. Wheeler. 



Stratagems op Birds. — A writer in the October 

 number asks if any of the readers of Science-Gossip 

 ever noticed a similar instance of birds using strata- 

 gem to decoy persons from the vicinity of their nest. 

 Quite a number of our American birds will behave 

 in a manner similar to the chaffinch mentioned, — 

 such as the quail, killdeer, prairie-hen, duck, turtle 

 dove, and, in fact, a majority of birds that build 

 their nests upou the ground, as many a rural youth 

 is able to testify from experience. — R. F. Kerr, 

 Greencaslle, Lid., U.S.A. 



Ticks on Mice.— About a month ago, whilst 

 taking a walk, I observed in my path a short-tailed 

 field-mouse, which appeared to be nibbling some- 

 thing on the ground. Ou touching it, instead of 

 running away as 1 expected, it rolled oyer, gasping, 

 and apparently in great pain, I carried it home, 



