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HE' outer "shell"

(if it may be so called), of the eggs of the majority of insects is composed of a chitinous membrane, of such protective toughness, that the eggs are frequently found in the crops of insectivorous birds, mixed with digested portions of food, so intact and unaltered in form, colour, and integrity, as possibly to be found to retain even their

vitality. In the article accompanying the plate of the egg of the house-fly in the October 1884 number of this journal, on page 218, an authentic case is referred to, of the eggs of the vapourer moth (Orgyia antiqua) having been found in large numbers in the intestines of a cuckoo, which was captured last August in the garden of the old Charterhouse School, London, and a detailed account of the circumstances published in the "Field" newspaper on the 30th of the same month. The present illustration shows a group of these eggs, after having been extracted, washed, and carefully dried; although the experiment was not tried, it is possible they might have been hatched.

The regularity of the various forms of the eggs of insects, added to exceptional appearances of colour, markings, and even sculptures, render them peculiarly attractive as microscopic objects. As a distinct subject of interest, they offer great diversity and beautyunlike the eggs of birds, exhibiting external appliances, strange structural appendages, fringes of extreme delicacy, eccentric forms and curvatures, with lids, No. 244.-APRIL 1885.

and caps of various devices to aid the emission of the larva.

It is not unworthy of note, that sculptured surfaces of rare beauty, raised nodules, pitted depressions, surrounded with ridges arranged with geometrical precision, radiating from the base to the apex, as found in the eggs of some insects, are peculiarities frequently seen in minute, and isolated germ life, in unicellular plants, the cells of desmids, diatoms, minute seeds, spores, and particularly in pollen granules where external appearances take the most singular and elegant forms.

The collector of the eggs of insects must be guided, in his explorations, by the habit of the parent. The suitable deposition of the egg, and its future development, depend on the supply and position of the food; it would be impossible to conceive an organism in a more helpless condition than a larva just emerged, unless it found itself surrounded by, or within reach of, abundant nutriment; the eggs of all leaf-eating caterpillars are consequently deposited on the branches, and in the interstices of the trees themselves, or in close proximity. Particular trees or plants, probably with some regard to locality and aspect, are selected by different species. In some cases the parent collects and stores the future food, depositing an egg in a cell, and packing it with just the amount required by the larva, anticipating a supply in proportion to the size of the cell which invariably is a sufficient, and an exact, quantity. Many of the vegetable-feeding beetles maintain the preservation of the future progeny by rolling up balls of food, in which is enveloped an egg-a case where the individual is evidently of less importance than the perpetuation of the species, the chances of survival being enhanced by the separate isolation of the egg. It is engagingly interesting to consider the powerful impulses which induce such actions; involving favourable positions, selection of herbage, and often temperature and moisture, as affecting the putrefaction or fermentation of organic substance in which the young maggots may revel, an impulse without doubt emanating from maternal presentiment

E

-for, in many cases progeny are actually nursed and protected by the parent, even supported and supplied with untiring zeal. As a rule insects are only destructive in a larval state-destructive, in many instances, in the sense of being beneficial. In that condition, development is rapid, and the chief business of life, i.e., the preparation for a higher and more important condition, is performed.

In consequence of the minuteness of eggs of insects, and the extraordinary care taken in depositing them, they frequently baffle detection, but it is certain few localities escape, and they may be sought for in the most unexpected, and apparently unlikely places. Many singular instances might be mentioned: the larvæ of the Curculios feed on the developing seeds of plants, the eggs are deposited in the flowers, and during growth, the hatched larvæ bore through the soft tissues of the "receptacle," and devour its contents. In the larger order of the lepidoptera extraordinary care is exhibited, even to the extent of mechanically providing protection by enveloping the eggs in peculiar coverings, or securing a defence with glue-like varnishes of considerable tenacity. The lifeduration of the egg condition, is often a factor. Many moths only deposit on fruits just ripening, a matter of days, and adjustment of time; unripe fruits are never touched. The cocci, or scale insects (infesting peachhouses, and conservatories), fix themselves firmly on the leaves and brood over the eggs; even after death the body forms a tent or covering under which the young remain until mature.

The orthoptera dig holes in the earth and deposit eggs in groups, enveloped in some instances in a case. As in this order the young when hatched immediately exhibit the lively appearance, appetites, and instincts of the parents, and are capable of at once seeking food, a storage of provision, or a contiguous supply is unnecessary. Living and growing tissues are often the nidus and receptacle of eggs. The gad-fly (Tabanus) has a sheath capable of penetrating the skins of animals, and not only depositing the egg, but of setting up a condition of excitement necessary for the future preservation of the young. The means and instruments employed are endless; the various forms of ovipositors is a subject in itself. They are capable of cutting into, and boring beneath the cuticles of leaves or the rinds of fruits, leaving an egg in the parenchyma, with the addition of a corrosive fluid of such virulence as to excite abnormal growths in aid of the sustenance of the future larvæ, producing contortions of tissues, and excrescences, as in the wellknown gall-nut; a curious reciprocity as affecting the functions of the plant, and the requirements of the insect.

Space does not admit the pursuit of this interesting subject; our younger readers must be referred to Kirby and Spence's most charming Introduction to Entomology.

Among remarkable forms may shortly be specified,

the yellow eggs of the cabbage butterfly (Pieris brassica), the puss moth (Cerura vinula), the privet moth (Sphinx ligustri), the transparent eggs of the honey bee, the cockroach, the cricket, and the eggs of most of the parasites, especially those infesting the pheasant. Many of these open longitudinally through well-marked sutures aided by the tension of curvature. For the cabinet, eggs are easily prepared as opaque objects, and it is not difficult to arrange them for observation on the stage of the microscope, in a living condition, showing the movement of the larva within, and with patient watching, its ultimate emergence.

Crouch End.

A

GOSSIP ON CURRENT TOPICS.

By W. MATTIEU WILLIAMS, F.R.A.S., F.C.S. VERY interesting paper on labour and wages in America was read at the Society of Arts by Mr. D. Pigeon, the Hon. J. Russell Lowell in the chair. Among many other facts proving the superior education afforded to artizans there, he showed that the number of public schools in the United States is 225,800, or one to every 200 of the entire population of both sexes and all ages. In Massachusetts alone there are nearly 2000 free libraries, or one to every Soo inhabitants. No wonder then that Mr. Lowell was able to say that "one thing he thought he had noticed in the real American workman, was the amount of brains which he mixed with his fingers," as compared with the workmen of other countries. Now that science is interfering with every kind of industry, this ability to mix up brains with fingers will determine the destiny of nations. Not only the arts of peace, but also the grim business of war, is dependent upon science. The victory of the Germans in the Franco-Prussian war was largely due to the mixing of brain with fingers, in the handling of delicate arms of precision, and the intelligent use of maps by common soldiers.

At the meeting of the Chemical Society, on 19th February, Mr. E. C. H. Francis described a simple but very valuable discovery, viz., that if filter paper be immersed in nitric acid of 142 sp. gr., and washed in water, it becomes remarkably toughened without losing its porosity, as when treated with sulphuric acid in making parchment paper. We are told that the paper treated with nitric acid may be washed and rubbed without damage, like linen. It contracts and loses a little weight, but contains no nitrogen. The weight of its ash diminishes, which is an advantage in analytical chemistry, especially in rough and ready commercial analyses where the ash is neglected. As non-chemical readers may not otherwise appreciate the important position held by filter paper in an analytical laboratory, I will explain

that in most cases the quantity of a given substance is determined by dissolving the mixture in which it is contained, and then adding a precipitant, which throws down the substance in question in solid insoluble form, usually a compound of known composition. The solid is separated by filtration and weighed. The filtering agent must be removable, and blotting paper answers the purpose admirably. If the precipitate is incombustible, the paper is burned with its adhering precipitate, which is then weighed. Otherwise, it is weighed on the paper, after drying; another piece of paper of equal size and proved equal weight, being used as counterpoise. Specially made paper that leaves but an infinitesimal ash is used.

In the Records of the Geological Survey of India, vol. 17, is a memoir by Dr. W. King, on the "Smooth Water Anchorages of Narrakal and Alleppy," on the Travancore Coast. These remain smooth even when the surface of the sea outside is torn by the southwesterly moonsoons into white surf-topped billows. The explanation of the mystery is simple enough, and is interesting, as affording further evidence on the disputed question of oiling the waves. The bottom of these anchorages is a soft, unctuous mud found to contain oil, and from it is a continuous oozing upwards of petroleum. My friend Arthur Robottom describes a similar calm region on the Californian coast, but at some distance out at sea. Here the oil wells up in large quantities, spreads visibly over the surface and effectively becalms a great area around the spring. Franklin's experiments on the ponds of Clapham Common, and his conclusion, that the oil prevents the wind from taking hold of the water, by acting as a lubricant against the wind-friction, are confirmed by these cases, by the experiments at Peterhead, and by all that has since been learned on the subject.

In the same volume is an account of a fiery eruption from one of the mud volcanoes on Cheduba Island, where a body of flame 600 feet in circumference is said to have at one time reached an elevation of 2400 feet. Petroleum again. The earth evidently contains a much larger store of petroleum than is usually supposed.

Very few people appreciate the interesting collection of meteorites in the British Museum. The majority of ordinary visitors pass through the whole of the show without seeing them at all. A very interesting addition is about to be made to this collection-will possibly be there when this is printed. It is a meteorite, weighing 46 kilos (101 lbs.), which was discovered in the autumn of 1882, near Durango, in Mexico, at a depth of about a foot. The slight depth and other indications have led to the inference that it had fallen quite recently. Its composition is: iron, 91 78; nickel, 8.35; cobalt, o'o1; with traces of phosphorus and carbon. Specific gravity, 7'74-7·89.

The detection of the ordinary adulteration of milk

by water is unsatisfactory, on account of the varying composition of the milk from different cows, and even from the same cow at different periods. The milk of an Alderney or Jersey cow may be much diluted, and yet, when tested by the proportion of water to cream, shall come out richer than the milk from some other cows when unmixed. The method recently introduced by M. Sambuc is said to overcome this difficulty. Experiments made by him in 1879, and in October and November of last year, show that the serum of the milk-that which is left when the casein and cream are removed, varies very little in specific gravity, never falling below 10278. To effect its separation, the milk is heated to 40°50° C. (104° to 122° F.), and an alcoholic solution of tartaric acid is added. After about a quarter of an hour the mixture is taken from the fire, agitated with a small bundle of twigs, and strained through a linen filter. The specific gravity of the serum or whey is then determined by a lactometer.

In Dingler's "Polytechnisches Journal," vol. 254, p. 443, is an account of a method of enamelling casks invented by F. G. Sponnagel, and apparently not patented. Instead of coating the wood with enamel, the cask or vat is first treated with an aqueous solution formed by fusing 100 parts of silica with 50 parts of alkali, and when this has penetrated the wood thoroughly the cask is filled with a solution of aluminium acetate in water mixed with sulphurous acid in the proportion of 4: 2: 1. This effects a precipitation of neutral enamel of silicate of alumina within the pores of the wood. Assuming that such precipitation is successfully effected, we obtain in such internally enamelled wood a material of great usefulness for a multitude of purposes besides cask making.

In the same volume of the same Journal, page 399, an honest method of manufacturing soap is described. Perhaps I should explain what I mean by honesty as applied in the manufacture of soap. Shrewd, observant house-wives know that bars of soap when stored in a dry place have a curious habit of shrinking, and that the amount of shrinkage varies with the samples. Not very long ago a petty fraud was rather extensively perpetrated by a gang of vagabonds, who strolled from door to door in poor neighbourhoods, offering "salvage soap " for sale. They told a tale of the shipwreck of a cargo of soap, and how it was damaged by sea water, how they had bought it cheap and could sell at three-halfpence or twopence per pound. The soap was sufficiently wet to correspond with the story. It contained 70 or 80 per cent. of water, on the evaporation of which a long bar shrivelled to a short twisted stick. Ordinary soap of fair quality contains 20 to 25 per cent. of water, but may be made to contain much more, even the salvage quantity. Pure soap is a compound of fatty acids with alkali, no free alkali remaining. Such remaining alkali renders it irritant to the skin, though suitable enough for washing greasy clothes or very dirty

people. In these cases the free alkali combines with the exuberant grease. In common yellow soap more or less of the fatty acid is replaced by resin.

The novelty to which I refer is the use of a centrifugal machine or drum, which is made to rotate very rapidly while containing the crude soap before it has been cooled. All the alkali or salt is thereby separated, and a larger quantity of the water; the soap is very dense and perfectly neutral, and therefore non-irritant. I may add, by way of warning, that among the fancy soaps is a vile compound, in which the fatty acids are more or less replaced by silicic acid. It is very smooth, lathers admirably, but treats tender skin most cruelly. One of the indications of the adulteration and of saline impurities generally is the efflorescence of very pretty crystals or the surface of the soap as it dries.

A more recent contribution of science to domestic economy has been discussed by the Hygienic Council of the Department of the Seine at Paris. It is the use of vaseline as a substitute for butter or fat in pastry. It appears that the chief motive of the pastry cook in adopting this "improvement" (?) is to obtain a pastry that will keep longer. From the tradesman's point of view this may be a desideratum, but to the consumer it is not so advantageous, seeing that this mineral grease is absolutely indigestible. It may slip through the digestive organs by virtue of its lubricating properties, and carry with it the particles of flour, sugar, &c., which it envelopes, but it cannot be assimilated, and probably protects the materials with which it is incorporated from the action of the digestive solvents. The strongest mineral acids do not disturb vaseline, neither do the most caustic alkalis saponify it. In the pastry it comes as vaseline and goes as vaseline, and probably does mischief in the course of its journey through the body. "The Council therefore advises that its use for pastry making shall not be permitted in France." Let us hope that such use may not be permitted in England. While M. Perrotin, director of the Nice Observatory, was making an observation on Hyperion, one of the satellites of Saturn, the object suddenly dashed to the right of the spider-line of the telescope, and then returned. It was the telescope that moved, and the earth that moved the telescope. A slight but sharp earthquake tremor occurred. This incident suggests a delicate means of measuring such move

ments.

WE have received the first number of a new monthly periodical, the "Journal of Mycology" (Manhattan, Kansas). It is intended to be a medium for the publication of matter of mycological interest; to note the discovery of new species of fungi, to give an account of the literature of the subject, and so assist in the extension of North American mycology in general.

THE VARIATION AND ABNORMAL DEVELOPMENT OF THE MOLLUSCA.

THE

HE variation of the Mollusca is an exceedingly interesting subject, but it is as vast as it is interesting. There seems to be hardly a species which, if sufficiently studied, does not present here and there some marked difference from what is known as the typical form; and some, as Helix nemoralis, are so variable, that two exactly similar specimens are rarely found. And this variation does not seem to rest on mere chance, but varieties are often local, abundant at one place, and not to be seen in the surrounding country: and, strangely enough, this localness seems also to be to a certain extent peculiar to what are generally called mere monstrosities. I mean the sinistral, scalariform, and decollated forms. Miss Hele, in SCIENCE-GOSSIP, records the occurrence of three sinistral Helix aspersa, and two H. hortensis, all in the same lane, and I cannot think that this was purely accidental; there must have been some reason for these shells becoming reversed, but what that reason may be, I cannot imagine. On Chislehurst Common I took a specimen of the monst. scalariforme of Limnæa stagnalis, having the whorls almost disunited, and the suture between the fourth and body whorl forming an acute angle. This specimen was found in a very small pond, where the typical form of L. stagnalis does not occur, but the pond is crowded with a variety, which is smaller than the type, and has a deeper suture. In the same pond my brother took another scalariform L. stagnalis, and he also found a third specimen in a pond not far off. Another brother (L. M. C.) has taken L. peregra, monst. scalariforme at St. Mary Cray, two miles from Chislehurst, and a scalariform Helix aspersa on Chislehurst Common. Whether there is any connection between the occurrences of these scalariform shells I do not know, but, if so, I suppose it must be due to the soil, or possibly, but not probably, to some parasite. I fancy the food has little or nothing to do with it, but I may as well mention that the pond in which the two scalariform L. stagnalis were found, contained Ranunculus aquatilis, and Potamogeton crispus, and the pond in which the other one was found contained Anacharis.

And now for an instance of decoliation. On Barnes Common I have found Bythinia tentaculata, monst. decollatum, Limnæa stagnalis, monst. decollatum, and a decollated specimen of L. palustris.* The decollation is most marked in the Bythinia, and less so in the Limnæa. Now in the instance of these Barnes specimens, I think there cannot be much doubt that the truncated spire is caused by a want of calcareous material in the water, and that, if a number of them were introduced into a pond containing a sufficient amount of carbonate of lime, the next

My brother (S.C.C.) has also taken the decollated form of L. peregra at Barnes.