These microscopic animals are believed to possess a power of generating others like themselves by solitary reproduction without sex; and these gradually enlarging and improving for innumerable successive generations. Mr. Ellis, in Phil. Transact. V. LIX. gives drawings of six kinds of animalcula infusoria, which increase by dividing across the middle into two distinct animals. Thus in paste composed of flour and water, which has been suffered to become acescent, the animalcules called eels, vibrio anguillula, are seen in great abundance; their motions are rapid and strong; they are viviparous, and produce at intervals a numerous progeny: animals similar to these are also found in vinegar. Naturalist's Miscellany by Shaw and Nodder, Vol. II. These eels were probably at first as minute as other microscopic animalcules; but by frequent, perhaps hourly reproduction, have gradually become the large animals above described, possessing wonderful strength and activity. To suppose the eggs of the former microscopic animals to float in the atmosphere, and pass through the sealed glass phial, is so contrary to apparent nature, as to be totally incredible! and as the latter are viviparous, it is equally absurd to suppose, that their parents float universally in the atmosphere to lay their young in paste or vinegar! Not only microscopic animals appear to be produced by a spontaneous vital process, and then quickly improve by solitary generation like the buds of trees, or like the polypus and aphis, but there is one vegetable body, which appears to be produced by a spontaneous vital process, and is believed to be propagated and enlarged in so short a time by solitary generation as to become visible to the naked eye; I mean the green matter first attended to by Dr. Priestley, and called by him conferva fontinalis. The proofs, that this material is a vegetable, are from its giving up so much oxygen, when exposed to the sunshine, as it grows in water, and from its green colour. Dr. Ingenhouz asserts, that by filling a bottle with well-water, and inverting it immediately into a basin of well-water, this green vegetable is formed in great quantity; and he believes, that the water itself, or some substance contained in the water, is converted into this kind of vegetation, which then quickly propagates itself. THEORY OF SPONTANEOUS VITALITY. IV. In animal nutrition the organic matter of the bodies of dead animals, or vegetables, is taken into the stomach, and there suffers decompositions and new combinations by a chemical process. Some parts of it are however absorbed by the lacteals as fast as they are produced by this process of digestion; in which circumstance this process differs from common chemical operations. In vegetable nutrition the organic matter of dead animals, or vegetables, undergoes chemical decompositions and new combinations on or beneath the surface of the earth; and parts of it, as they are produced, are perpetually absorbed by the roots of the plants in contact with it; in which this also differs from common chemical processes. Hence the particles which are produced from dead organic matter by chemical decompositions or new consequent combinations, are found proper for the purposes of the nutrition of living vegetable and animal bodies, whether these decompositions and new combinations are performed in the stomach or beneath the soil. For the purposes of nutrition these digested or decomposed recrements of dead animal or vegetable matter are absorbed by the lacteals of the stomachs of animals or of the roots of vegetables, and carried into the circulation of their blood, and these compose new organic parts to replace others which are destroyed, or to increase the growth of the plant or animal. It is probable, that as in inanimate or chemical combinations, one of the composing materials must possess a power of attraction, and the other an aptitude to be attracted; so in organic or animated compositions there must be particles with appetencies to unite, and other particles with propensities to be united with them. Thus in the generation of the buds of trees, it is probable that two kinds of vegetable matter, as they are separated from the solid system, and float in the circulation, become arrested by two kinds of vegetable glands, and are then deposed beneath the cuticle of the tree, and there join together, forming a new vegetable, the caudex of which extends from the plumula at the summit to the radicles beneath the soil, and constitutes a single fibre of the bark. These particles appear to be of two kinds; one of them possessing an appetency to unite with Mr. Girtanner asserts, that this green vegeta- the other, and the latter a propensity to be unitble matter is not produced by water and heated with the former; and they are probably separalone, but requires the sun's light for this purpose, as he observed by many experiments, and thinks it arises from decomposing water deprived of a part of its oxygen, and laughs at Dr. Priestley for believing that the seeds of this conferva, and the parents of microscopic animals, exist universally in the atmosphere, and penetrate the sides of glass jars. Philos. Magazine for May 1800. Besides this green vegetable matter of Dr. Priestley, there is another vegetable, the minute beginnings of the growth of which Mr. Ellis observed by his microscope near the surface of all putrefying vegetable or animal matter, which is the mucor or mouldiness; the vegetation of which was amazingly quick, so as to be almost seen, and soon became so large as to be visible to the naked eye. It is difficult to conceive how the seeds of this mucor can float so universally in the atmosphere as to fix itself on all putrid matter in all places. ated from the vegetable blood by two kinds of glands, one representing those of the anthers, and the others those of the stigmas, in the sexual organs of vegetables; which is spoken of at large in Phytologia, Sect. VII. and in Zoonomia, Vol. I. Sect. XXXIX. 8. of the third edition, in octavo; where it is likewise shown, that none of these parts which are deposited beneath the cuticle of the tree, is in itself a complete vegetable embryon, but that they form one by their reciprocal conjunction. So in the sexual reproduction of animals, certain parts separated from the living organs, and floating in the blood, are arrested by the sexual glands of the female, and others by those of the male. Of these none are complete embryon animals, but form an embryon by their reciprocal conjunction. There hence appears to be an analogy between generation and nutrition, as one is the production of new organization, and the other the re storation of that which previously existed; and which may therefore be supposed to require materials somewhat similar. Now the food taken up by animal lacteals is previous ly prepared by the chemical process of digestion in the stomach; but that which is taken up by vegetable lacteals, is prepared by chemical dissolution of organic matter beneath the surface of the earth. Thus the particles, which form generated animal embryons, are prepared from dead organic matter by the chemico-animal processes of sanguification and of secretion; while those which form spontaneous microscopic animals or microscopic vegetables are prepared by chemical dissolutions and new combinations of organic matter in watery fluids with sufficient warmth. years or longer, and have revived on being moistened 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 moisture, retain some dogree of vitality, since this is done by more complicate animal organs in the instances above mentioned. The hydra of Linnæus, which dwells in the rivers of Europe under aquatic plants, has been observed by the curious of the present time, to revive after it has been dried, to be restored after being mutilated, to multiply by being divided, to be propagated from small portions, to live after being inverted; all which would be best explained by the doctrine of spontaneous reproduction from organic particles not yet completely decomposed. 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. To this should be added, that these microscoThus the elastic gum, or caoutchouc, and pic animals are found in all solutions of vegesome fossile bitumens, when drawn out to a table or animal matter in water; as black pepgreat length, contract themselves by their elas- per steeped in water, hay suffered to become ticity, like an animal fibre by stimulus. The putrid in water, and the water of dunghills, aflaws of action of these, and all other elastic ford animalcules in astonishing numbers. See bodies, are not yet understood; as the laws of Mr. Ellis's curious account of Animalcules prothe attraction of cohesion, to produce these effects, duced from an infusion of Potatoes and Hempmust be very different from those of general at- seed; Philos. Transact. Vol. LIX. from all traction, since the farther the particles of elastic which it would appear, that the organic particles bodies are drawn from each other till they sepa- of dead vegetables and animals during their usual rate, the stronger they seem to attract; and the chemical changes into putridity or acidity, do nearer they are pressed together, the more they not lose all their organization or vitality, but seem to repel; as in bending a spring, or in ex- retain so much of it as to unite with the parts tending a piece of elastic gum; which is the re- of living animals in the process of nutrition, or verse to what occurs in the attractions of dis- unite and produce new complicate animals by united bodies; and much wants further investi- secretion as in generation, or produce very simple gation. So the spontaneous production of alco- microscopic animals or microscopic vegetables, hol or of vinegar, by the vinous and acetous fer- by their new combinations in warmth and mentations, as well as the production of a mucus moisture. by putrefaction which will contract when extended, seems almost as difficult to understand as the spontaneous production of a fibre from decomposing animal or vegetable substances, which will contract when stimulated, and thus constitutes the primordium of life. Some of the microscopic animals are said to remain dead for many days or weeks, when the fluid in which they existed is dried up, and quickly to recover life and motion by the fresh addition of water and warmth. Thus the chaos redivivum of Linnæus dwells in vinegar and in bookbinders' paste: it revives by water after having been dried for years, and is both oviparous and vivaparous. 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 tops 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 globulous 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 about, lengthens itself by slow degrees, assumes the form of a lively maggot, and most commonly in a few minutes afterwards puts out its wheels, swimming vigorously through the water as if in search of food; or else, fixing itself by the tail, works the wheels in such a manner as to bring its food to its mouth.-English Encycl. Art. Animalcule. Thus some shell-snails in the cabinets of the curious have been kept in a dry state for ten And finally, that these microscopic organic bodies are multiplied and enlarged by solitary reproduction without sexual intercourse till they acquire greater perfection or new properties. Lewenhoek observed in rain water which had stood a few days, the smallest scarcely visible microscopic animalcules, and in a few more days he observed others eight times as large. — English Encyclop. Art. Animalcule. CONCLUSION. There is therefore no absurdity in believing that the most simple animals and vegetables may be produced by the congress of the parts of decomposing organic matter, without what can properly be termed generation, as the genus did not previously exist; which accounts for the endless varieties, as well as for the immense numbers of microscopic animals. The green vegetable matter of Dr. Priestley, which is universally produced in stagnant water, and the mucor, or mouldiness, which is seen on the surface of all putrid vegetable and animal matter, have probably no parents, but a spontaneous origin from the congress of the decomposing organic particles, and afterwards propagate themselves. Some other fungi, as those growing in close wine-vaults, or others which arise from decaying trees, or rotten timber, may perhaps be owing to a similar spontaneous production, and not previously exist as perfect organic beings in the juices of the wood, as some have supposed. In the same manner it would seem, that the common esculent mushroom is produced from horse dung at any time and in any place, as is the common practice of many garden- | ed, they are seen to flock towards the remaining ers.-Kennedy on Gardening. APPENDIX. THE knowledge of microscopic animals is still in its infancy: those already known are arranged by Mr. Muller into the following classes; but it is probable, that many more classes, as well as innumerable individuals, may be discovered by improvements of the microscope, as Mr. Herschell has discovered so many thousand stars, which were before invisible, by improvements of the telescope. Mr. Muller's classes consist of I. SUCH AS HAVE NO EXTERNAL ORGANS. 1. Monas: Punctiformis. A mere point. 2. Proteus: Mutabilis. Mutable. 3. Volvox: Sphæricum. Spherical. 4. Enchelis: Cylindracea. Cylindrical. 5. Vibrio: Elongatum. Long. *Membranaceous. 6. Cyclidium: Ovale. Oval. II. THOSE THAT HAVE EXTERNAL ORGANS. 3. Kerona: Corniculatum. With horns. 4. Himantopus: Cirratum. Cirrated. 5. Leucophra: Ciliatum undique. Every part ciliated. 6. Vorticella: Ciliatum apice. ciliated. *Covered with a shell. 7. Brachionus: Ciliatum apice. ciliated. The apex The apex 1. These animalcules are discovered in two or three days in all decompositions of organic matter, whether vegetable or animal, in moderate degrees of warmth with sufficient moisture. 2. They appear to enlarge in a few days, and some to change their form; which are probably converted from more simple into more complicate animalcules by repeated reproductions. See Note VIII. 3. In their early state they seem to multiply by viviparous solitary reproduction, either by external division, as the smaller ones, or by an internal progeny, as the eels in paste or vinegar; and lastly, in their more mature state, the larger ones are said to appear to have sexual connexion. Engl. Encyclop. part, and show great agitation. They sustain a great degree of cold, as some insects, and perish in much the same degree of heat as destroys insects; all which evince that they are living animals. And it is probable, that other or similar animalcules may be produced in the air, or near the surface of the earth, but it is not so easy to view them as in water; which as it is transparent, the creatures produced in it can easily be observed by applying a drop to a microscope. I hope that microscopic researches may again excite the attention of philosophers, as unforeseen advantages may probably be derived from them, like the discovery of a new world. NOTE II.-THE FACULTIES OF THE Next the long nerves unite their silver train, I. THE fibres, which constitute the muscles and organs of sense, possess a power of contraction. The circumstances attending the exertion of this power of contraction constitute the laws of animal motion, as the circumstances attending the exertion of the power of attraction constitute the laws of motion of inanimate matter. II. The spirit of animation is the immediate cause of the contraction of animal fibres, it resides in the brain and nerves, and is liable to general or partial diminution or accumulation. III. The stimulus of bodies external to the moving organ is the remote cause of the original contractions of animal fibres. IV. A certain quantity of stimulus produces irritation, which is an exertion of the spirit of animation exciting the fibres into contraction. V. A certain quantity of contraction of animal fibres, if it be perceived at all, produces pleasure; a greater or less quantity of contraction, if it be perceived at all, produces pain; these constitute sensation. VI. A certain quantity of sensation produces desire or aversion; these constitute volition. VII. All animal motions which have occurred at the same time, or in immediate succession, become so connected, that when one of them is reproduced, the other has a tendency to accompany or succeed it. When fibrous contractions succeed or accompany other fibrous contractions, the connexion is termed association; when fibrous contractions succeed sensorial motions, the connexion is termed causation; when fibrous and sensorial motions reciprocally introduce each other, it is termed catenation of animal motions. Irritation is an exertion or change cf some extreme part of the sensorium residing in the muscles or organs of sense, in consequence of the appulses of external bodies. 4. Those animalcules discovered in pustules VIII. These four faculties of the sensorium of the itch, in the feces of dysenteric patients, during their inactive state are termed irritabiland in semine masculino, I suppose to be pro-ity, sensibility, voluntarity, and associability; duced by the stagnation and incipient decompo- in their active state they are termed as above, irsition of those materials in their receptacles, and ritation, sensation, volition, association. not to exist in the living blood or recent secretions; as none, I believe, have been discovered in blood when first drawn from the arm, or in fluids newly secreted from the glands, which have not previously stagnated in their reservoirs. 5. They are observed to move in all directions with ease and rapidity, and to avoid obstacles, and not to interfere with each other in their motions. When the water is in part evaporat Sensation is an exertion or change of the central parts of the sensorium, or of the whole of it, beginning at some of those extreme parts of it, which reside in the muscles or organs of sense. Volition is an exertion or change of the central parts of the sensorium, or of the whole of it, terminating in some of those extreme parts of it, which reside in the muscles or organs of sense. Association is an exertion or change of some extreme part of the sensorium residing in the muscles or organs of sense, in consequence of some antecedent or attendant fibrous contractions. See Zoonomia, Vol. I. The word sensorium is used to express not only the medullary part of the brain, spinal marrow, nerves, organs of sense and muscles, but also at the same time that living principle, or spirit of animation, which resides throughout the body, without being cognizable to our senses except by its effects. NOTE III.-VOLCANIC FIRES. Next when imprison'd fires in central caves Burst the firm earth, and drank the headlong waves. CANTO I. 1. 302. THE great and repeated explosions of volcanoes are shown by Mr. Mitchell in the Philos. Trans. to arise from their communication with the sea, or with rivers, or inundations; and that after a chink or crack is made, the water rushing into an immense burning cavern, and falling on boiling lava, is instantly expanded into steam, and produces irresistible explosions. As the first volcanic fires had no previous vent, and were probably more central, and larger in quantity, before they burst the crust of the earth then entire, and as the sea covered the whole, it must rapidly sink down into every opening chink; whence these primeval earthquakes were of much greater extent, and of much greater force, than those which occur in the present era. It should be added, that there may be other elastic vapours produced by great heat from whatever will evaporate, as mercury, and even diamonds; which may be more elastic, and consequently exert greater force than the steam of water even though heated red hot; which may thence exert a sufficient power to raise islands and continents, and even to throw the moon from the earth. If the moon be supposed to have been thus thrown out of the great cavity which now contains the South Sea, the immense quantity of water flowing in from the primeval ocean, which then covered the earth, would much contribute to leave the continents and islands, which might be raised at the same time above the surface of the water. In later days there are accounts of large stones falling from the sky, which may have been thus thrown by explosion from some distant earthquake, without sufficient force to cause them to circulate round the earth, and thus produce numerous small moons or satellites. neous fires at some great depth beneath those parts of this island. See on this subject Botanic Garden, Part II. Canto IV. 1. 79," note. For an account of the noxious vapours emitted from volcanoes, see Botanic Garden, Part II. Canto IV. 1. 328, note. For the milder effects of central fires, see Botanic Garden, Part I. Canto I. 1. 139, and Additional Note VI. NOTE IV.-MUSQUITO. So from deep lakes the dread musquito springs, Drinks the soft breeze, and dries his tender wings. CANTO I. 1. 327. THE gnat, or musquito, culex pipiens. The larva of this insect lives chiefly in water, and the pupa moves with great agility. It is fished for by ducks; and when it becomes a fly, is the food of the young of partridges, quails, sparrows, swallows, and other small birds. The females wound us, and leave a red point; and in India their bite is more venomous. The male has its antennæ and feelers feathered, and seldom bites or sucks blood. Lin. Syst. Nat. It may be driven away by smoke, especially by that from inula helenium, elecampane; and by that of cannabis, hemp. Kalm. It is said that a light in a chamber will prevent their attack on sleeping persons. The gnats of this country are produced in greater numbers in some years than others, and are then seen in swarms for many evenings near the lakes or rivers whence they arise; and, I suppose, emigrate to upland situations, where fewer of them are produced. About thirty years ago such a swarm was observed by Mr. Whitehurst for a day or two about the lofty tower of Derby church, as to give a suspicion of the fabric being on fire. Many other kinds of flies have their origin in the water, as perhaps the whole class of neuroptera. Thus the libellula, dragon fly: the larva of which hurries amid the water, and is the cruel crocodile of aquatic insects. After they become flies, they prey principally on the class of insects termed lepidoptera, and diptera of Linneus. The ephemera is another of this order, which rises from the lakes in such quantities in some countries, that the rustics have carried cart-loads of them to manure their corn lands; the larva swims in the water: in its flystate the pleasures of life are of short duration, as its marriage, production of its progeny, and funeral, are often celebrated in one day. The phryganea is another fly of this order; the larva lies concealed under the water in moveable cylindrical tubes of their own making. In the fly-state they insinuate evening dances in the air in swarms, and are fished for by the swallows. Many other flies, who do not leave their eggs in water, contrive to lay them in moist places, as the oestros bovis; the larvæ of which exist in the bodies of cattle, where they are nourished Mr. Mitchell observes, that the agitations of during the winter, and are occasionally extractthe earth from the great earthquake at Lisboned by a bird of the crow-kind called buphaga. were felt in this country about the same time after the shock, as sound would have taken in passing from Lisbon hither; and thence ascribes these agitations to the vibrations of the solid earth, and not to subterraneous caverns of communication. Philos. Transact. But from the existence of warm springs at Bath and Buxton, there must certainly be unceasing subterra These larvæ are also found in the stomachs of horses, whom they sometimes destroy; another species of them adhere to the anus of horses, and creep into the lowest bowel, and are called botts and another species enters the frontal sinus of sheep, occasioning a vertigo called the turn. The musca pendula lives in stagnant water; the larva is suspended by a thread-form respiratory I D. D. Garden dissected the amphibious creature called diodon by Linneus, and was amazed to find that it possessed both external gills and internal lungs, which he described and prepared and sent to Linneus; who thence put this animal into the order nantes of his class amphibia. He adds also, in his account of polymorpha before the class amphibia, that some of this class breathe by lungs only, and others by both lungs and gills. had power to decompose the water and obtain the oxygen from it. The lamprey, petromyzon, is put by Linneus among the nantes, which are defined to possess both gills and lungs. It has seven spiracula, or breathing holes, on each side of the neck, and by its more perfect lungs approaches to the serpent kind. Syst. Nat. The means by which it adheres to stones, even in rapid streams, is probably owing to a partial vacuum made by its respiring organs like sucking, and may be compared to the ingenious method by which boys are seen to lift large stones in the street, by applying to them a piece of strong moist leather with a string through the centre of it; which, when it is forcibly drawn upwards, produces a partial vacuum under it, and thus the stone is supported by the pressure of the atmosphere. The leech, hirudo, and the remora, echeneis, adhere strongly to objects probably by a similar method. I once saw ten or twelve leeches adhere to each foot of an old horse a little above his hoofs, who was grazing in a morass, and which did not lose their hold when he moved about. The bare-legged travellers in Ceylon are said to be much infested by leeches; and the sea-leech, hirudo muricata, is said to adhere to fish, and the remora is said to adhere to ships in such numbers as to retard their progress. The respiratory organ of the whale, I suppose, is pulmonary in part, as he is obliged to come frequently to the surface, whence he can be pursued after he is struck with the harpoon; and may nevertheless be in part like the gills of other fish, as he seems to draw in water when he is below the surface, and emits it again when he rises above it. Some amphibious quadrupeds, as the beaver, water rat, and otter, are said to have the foramen ovale of the heart open, which communicates from one cavity of it to the other; and that, during their continuance under water, the blood can thus for a time circulate without passing through the lungs; but as it cannot by these means acquire oxygen either from the air or water, these creatures find it frequently necessary to rise to the surface to respire. As this foramen ovale is always open in the foetus of quadrupeds, till after its birth that it begins to respire, it has been proposed by some to keep young puppies three or four times a day for a minute or two under warm water to prevent this communication from one cavity of the heart | NOTE VI.-HIEROGLYPHIC CHARto the other from growing up; whence it has been thought such dogs might become amphibious. It is also believed that this circumstance has existed in some divers for pearl; whose children are said to have been thus kept under water in their early infancy to enable them afterwards to succeed in their employment. But the most frequent distinction of the amphibious animals, that live much in the water, is, that their heart consists but of one cell; and as they are pale creatures with but little blood, and that colder and darker coloured, as frogs and lizards, they require less oxygen than the warmer animals with a greater quantity and more scarlet blood; and thence, though they have only lungs, they can stay long under water without great inconvenience; but are all of them, like frogs, and crocodiles, and whales, necessitated frequently to rise above the surface for air. In this circumstance of their possessing a onecelled heart, and colder and darker blood, they approach to the state of fish; which thus appear not to acquire so much oxygen by their gills from the water as terrestrial animals do by their lungs from the atmosphere; whence it may be concluded that the gills of fish do not decompose the water which passes through them, and which contains so much more oxygen than the air, but that they only procure a small quantity of oxygen from the air which is diffused in the water; which also is further confirmed by an experiment with the air-pump, as fish soon die when put in a glass of water into the exhausted receiver, which they would not do if their giils ACTERS. So erst as Egypt's rude designs explain. CANTO I. 1. 351. THE outlines of animal bodies, which gave names to the constellations, as well as the characters used in chemistry for the metals, and in astronomy for the planets, were originally hieroglyphic figures, used by the magi of Egypt before the invention of letters, to record their discoveries in those sciences. Other hieroglyphic figures seem to have been designed to perpetuate the events of history, the discoveries in other arts, and the opinions of those ancient philosophers on other subjects. Thus their figures of Venus for beauty, Minerva for wisdom, Mars and Bellona for war, Hercules for strength, and many others, became afterwards the deities of Greece and Rome; and together with the figures of Time, Death, and Fame, constitute the language of the painters to this day. From the similarity of the characters which designate the metals in chemistry, and the planets in astronomy, it may be concluded that these parts of science were then believed to be connected; whence astrology seems to have been a very early superstition. These, so far, constitute an universal visible language in those sciences. So the glory, or halo, round the head is a part of the universal language of the eye, designating a holy person; wings on the shoulders denote a good angel; and a tail and hoof denote the figure |