OCR Text |
Show 6 Additional Notes. anthers, and the others those of the stigmas, in the sexual organs of vegetables; which is spoken of at large in Phytologia, ct. VII. and in Zoonomia, Vol. I. Sect. XXXIX. 8. of the third dition, in octavo; where it is likewise shown, that none of these parts which arc deposited beneath the cuticle of the tree, is in it elf a ·ompl te vco·etablc cmbryon, bnt that they form one by th ir reciprocal conjunction. So in the sexual reproduction of animals, c 'ttain parts separated from the living oro·ans, and floatinr· in the blood, arc arrested by the sexmtl glands of the female, and others by those of the nnlc. Of these none ar complete embryon animals, but form an embryon by their reciprocal conjunction. Thcr hence appears to be an analogy between generation and uutritiou, as one i the production of new organization, and the other the restoration of that which previou ly existed; and which may therefore be supposed to require materials somewhat similar. Now the food taken up by animal lacteaLs 1s previously pr par d by the chemical process of digestion in the stomach; but that which is 'taken up by vegetable 1a.ctcals, is prepared by chemical dis olution of organic inatter beneath the surface of the earth. Thus the parti ·le , which form generated animal embryons, are prepared from dead organic matter by the chcmico-animal.processes of sanguification and of secretion; while those which form spontaneous micro copic animals or microscopic vegetables are prepared by chemical dissolutions and new combinations of organic matter in ·watery fluids with sufficicn t warmth. It may be here added, that the production and properties of some kinds of inanimate matter, are almost as difficult to comprehend as those of the simplest degrees of animation. Thus the elastic gum, or caoutchouc, and some fossile bitumens, when drawn out to a great lengt~1, contract themselves by their elasticity, like an animal fibre by stimulus. The laws of action of these, and all other elastic bod ics, are not yet understood; as the laws of the -attraction of cohe ion to produce these effects, must be very different from those of o·e1: eral attraction, since the farther the particles of elastic bodies arc0 drawn from each other till they separate, the str~nger they seem to attract; and the ~~carer t.hey are pressed together, the more they seem to .repel; as m bendmg a spring, or in extending a piece of elastic gum; Spontaneous Vitality oj' Microscopic .Animals. 7 which is the reverse to what occurs in the attractions of disunited bodies· and much wants further investigation. So the spontaneous productio~ of alcohol or of vinegar, by the vinous and acetous fermentations, as well as the production of a mucus by putrefaction which will contract when extended: seems almost as difficult to understand as the sponta· ueou productwn of a fibre from decomposing animal or vegetable substances, which will contract when stimulated, and thus constitutes the primordium of life. Some of the micro eopic animals are said to remain dead for many days or weeks, when the fluid iu whi ch they exi ted is dried up, and quickly to recover life and motion by the fresh addition of water and warmth. Thus the chaos redivivum of Linureus dwells in vinegar and in bookbiaders paste: it revives by water after having been dried for years, and is both oviparous and viviparous; Syst. Nat. Thus the vorticella or wheel animal, which is found in rain water that has stood some days in leaden gutters, or in hollows of lead on the top of houses, or in the slime or sediment left by such water, though it discovers no sign of life except when in the water, yet it is capable of continuing alive for many months though kept in a dry state. In this state it is of a glolmlous shape, exceeds not the bigness of a grain of sand, and no signs of life appear; but being put into water, in the space of half an hour a languid motion begins, the globule turns itself ahout, lengthens it elf by slow degrees, assumes the form of a lively maggot, ancl most commonly in a few minutes afterwards puts out its wheels, swimming vigorously through the water as if in search of food; or else, Jlxing itself by the tail, works the wheels in such a. manner as to bring its food to its mouth; English Encyclopedia, Art. Animalcule. Thus some shell-snails in the cabinets of the curjous have been kept in a dry state for ten years or longer, and. have revived on being moi tened with warmish water; Philos. Transact. So eggs and seeds after many months torpor, are revived by warmth and moisture; hence it may be concluded, that even the organic particles of dead animals may, when exposed to a due degree of warmth and mois hue, regain some degree of vitality, since this is done by more complicate animal organs in the instances above mentioned. |