Goldsmith's Natural history : with notes from all the popular treatises that have been issued since the time of Goldsmith ... / [edited] by Henry Innes, with a life of Oliver Goldsmith by George Moir Bussey.

Oliver Goldsmith

Date:: [18??]

Credit: Goldsmith's Natural history : with notes from all the popular treatises that have been issued since the time of Goldsmith ... / [edited] by Henry Innes, with a life of Oliver Goldsmith by George Moir Bussey. Source: Wellcome Collection.

796/860 page 420

$4*20 For (bis purpose, a room is chosen with a south aspert, and tlie windows are so well plazed. as not to admit the Isast air; the walls are well built, and the- planks of the floor exceedingly close, so as to admit neither birds nor mice, nor even so much as an insect. In the middle there should be four pillars erected, or four wooden posts, so placed as to form a pretty large square. Between these are different stories made with ozier hurdles, and under each hurdle there should be a floor, with an upright border all round. These hurdles and floors must hang upon pulleys, so as to be placed or taken down at pleasure. When the worms are hatched, some tender mulberry-leaves are provided, and placed in the cloth or paper box in which the eggs were kid, and which are large enough to hold a great number. When they have acquired some strength, they must be distributed on beds of mulberry-leaves, in the ditferent stories of the square in the middle of the room, round which a person may freely pass on every side. They will fix themselves to the leaves, and afterqrards to the sticks of the hurdles, when the leaves are devoured. They have then a thread, by which they can suspend themselves on occasion, to prevent any shock by a fall; but this is by no means to be considered as the silk which they spin afterwards in such abundance. Care must be taken that fresh leaves be brought every morning, which must be strewed very gently and equally over them ; upon tloes not happen to eggs, though subjected to cold of much greater intensity. Their con- tents remain fluid, even at the greatest cold, as may be seen by crushing them with the nail. Perhaps this is derived from consti- tuent spirituous or oleaginous parts, or from some principle adapted to abate the power of cold. If eggs do not freeze, it is probable the included embryos do not freeze. Is there anything wonderful, therefore, that they then survive cold which is fatal to them when pro- duced ? Probably for the same reason (and I see no objection that can apply), animalcula, concentrated in the germ, can support a de- gree of cold they are incapable of when de- velopwl. “ .A.S the tem|>erature of freezing still re- tains a portion of heat, why, it may be asked, should it not develope the germs of the most minute animalcula ? Had we never seen any eggs hatched but those of birds, which recpiire 104°, we should have concluded that all others require the same. A little initia- tion into the study of minute animals teaches how many kinds produce at a temperature infinitely less. Such are the eggs of butter- flies and many other insects, of frogs, lizards, tortoises, down to some, as those of toads, which I have seen produce at 45°. If these eggs hatch at 59° less than is required by those of binls, what repugnance will there be to suppose that at 1^ less, or the freezing point, the eggs of other animals may be hatched ? Nor should it surprise me to be told of animals whose eggs would produce at much greater cold, after knowing that there are plants, beings so similar to animals, and many of them, which amidst the rigours of winter flourish and fructify.” It is remarked by John Hunter, that an egg will freeze by a great degree of cold ; at the same time there seems to be a living principle which enables it to support cold without destruction, and when once that principle is destroyed, cokl more easily ope- rates. An egg was thus frozen by the cold of zero ; after thawing and again exposing it to the same degree of cold, it froze seven minutes and a half sooner. A new-laid egg took an hour to freeze in 15° and 17°, but when thawed, it froze at 25° in half the time. The principle of vitality, therefore, what- ever may be the cause, is evidently less easily destroyed in the egg state than in the perfect animal; and, therefore, the inference that a rigorous winter promises a diminution of in- sects in the summer succeeding commonly proves erroneous. On the contrary, recorded facts prove that they are sometimes even more abundant than usual after severe frosts. During the present spring of 1830, accord- ingly, notwithstanding the severe frosts of the preceding winter, we have observed a much greater number of insects, even of the smaller and more delicate kinds (aleyrudes, corethra, alucita, §-c.) as well as of lurvse, both those just hatched, and those which have lived through the winter, than last year, when the frost was not so severe. We were particularly struck with the larvae of some small tipula {boletophila ?), which we found in abundance in Birch-wood, Kent, feeding on a fungus {l/oleivs fomentarius, Fries), and which were so beautifully transparent and soft, that we could not understand how they had escaped being frozen. It is not a little remarkable, in connexion with this, that the migratory birds seem to have been aware of this abundance of insects by their apjiear- ing earlier than usual. We saw a ])air of nightingales at Greenhithe on the 2l8t of March, and a number of swallows the same week at Lee,—which is two or three weeks before their average lime.—Insecj- Tkans.$