The Temple of Nature; or, the Origin of Society - A Poem, with Philosophical Notes
by Erasmus Darwin
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"When rapp'd CECILIA breathes her matin vow, And lifts to Heaven her fair adoring brow; 330 From her sweet lips, and rising bosom part Impassion'd notes, that thrill the melting heart; Tuned by thy hand the dulcet harp she rings, And sounds responsive echo from the strings; Bright scenes of bliss in trains suggested move, And charm the world with melody and love.

III. "SOON the fair forms with vital being bless'd, Time's feeble children, lose the boon possess'd; The goaded fibre ceases to obey, And sense deserts the uncontractile clay; 340 While births unnumber'd, ere the parents die, The hourly waste of lovely life supply; And thus, alternating with death, fulfil The silent mandates of the Almighty Will; Whose hand unseen the works of nature dooms By laws unknown—WHO GIVES, AND WHO RESUMES.

[Footnote: The goaded fibre, l. 339. Old age consists in the inaptitude to motion from the inirritability of the system, and the consequent want of fibrous contraction; see Additional Note VII.]

"Each pregnant Oak ten thousand acorns forms Profusely scatter'd by autumnal storms; Ten thousand seeds each pregnant poppy sheds Profusely scatter'd from its waving heads; 350 The countless Aphides, prolific tribe, With greedy trunks the honey'd sap imbibe; Swarm on each leaf with eggs or embryons big, And pendent nations tenant every twig. Amorous with double sex, the snail and worm, Scoop'd in the soil, their cradling caverns form; Heap their white eggs, secure from frost and floods, And crowd their nurseries with uncounted broods. Ere yet with wavy tail the tadpole swims, Breathes with new lungs, or tries his nascent limbs; 360 Her countless shoals the amphibious frog forsakes, And living islands float upon the lakes. The migrant herring steers her myriad bands From seas of ice to visit warmer strands; Unfathom'd depths and climes unknown explores, And covers with her spawn unmeasured shores. —All these, increasing by successive birth, Would each o'erpeople ocean, air, and earth.

[Footnote: Ten thousand seeds, l. 349. The fertility of plants in respect to seeds is often remarkable; from one root in one summer the seeds of zea, maize, amount to 2000; of inula, elecampane, to 3000; of helianthus, sunflower, to 4000; of papaver, poppy, 32000; of nicotiana, tobacco, to 40320; to this must be added the perennial roots, and the buds. Buds, which are so many herbs, in one tree, the trunk of which does not exceed a span in thickness, frequently amount to 10000; Lin. Phil. Bot. p. 86.]

[Footnote: The countless Aphides, l. 351. The aphises, pucerons, or vine-fretters, are hatched from an egg in the early spring, and are all called females, as they produce a living offspring about once in a fortnight to the ninth generation, which are also all of them females; then males are also produced, and by their intercourse the females become oviparous, and deposite their eggs on the branches, or in the bark to be hatched in the ensuing spring.

This double mode of reproduction, so exactly resembling the buds and seeds of trees, accounts for the wonderful increase of this insect, which, according to Dr. Richardson, consists of ten generations, and of fifty at an average in each generation; so that the sum of fifty multiplied by fifty, and that product again multiplied by fifty nine times, would give the product of one egg only in countless millions; to which must be added the innumerable eggs laid by the tenth generation for the renovation of their progeny in the ensuing spring.]

[Footnote: The honey'd sap, l. 352. The aphis punctures with its fine proboscis the sap-vessels of vegetables without any visible wound, and thus drinks the sap-juice, or vegetable chyle, as it ascends. Hence on the twigs of trees they stand with their heads downwards, as I have observed, to acquire this ascending sap-juice with greater facility. The honey-dew on the upper surface of leaves is evacuated by these insects, as they hang on the underside of the leaves above; when they take too much of this saccharine juice during the vernal or midsummer sap-flow of most vegetables; the black powder on leaves is also their excrement at other times. The vegetable world seems to have escaped total destruction from this insect by the number of flies, which in their larva state prey upon them; and by the ichneumon fly, which deposits its eggs in them. Some vegetables put forth stiff bristles with points round their young shoots, as the moss-rose, apparently to prevent the depredation of these insects, so injurious to them by robbing them of their chyle or nourishment.]

[Footnote: The tadpole swims, l. 359. The progress of a tadpole from a fish to a quadruped by his gradually putting forth his limbs, and at length leaving the water, and breathing the dry air, is a subject of great curiosity, as it resembles so much the incipient state of all other quadrupeds, and men, who are aquatic animals in the uterus, and become aerial ones at their birth.]

"So human progenies, if unrestrain'd, By climate friended, and by food sustain'd, 370 O'er seas and soils, prolific hordes! would spread Erelong, and deluge their terraqueous bed; But war, and pestilence, disease, and dearth, Sweep the superfluous myriads from the earth. Thus while new forms reviving tribes acquire Each passing moment, as the old expire; Like insects swarming in the noontide bower, Rise into being, and exist an hour; The births and deaths contend with equal strife, And every pore of Nature teems with Life; 380 Which buds or breathes from Indus to the Poles, And Earth's vast surface kindles, as it rolls!

[Footnote: Which buds or breathes, l. 381. Organic bodies, besides the carbon, hydrogen, azote, and the oxygen and heat, which are combined with them, require to be also immersed in loose heat and loose oxygen to preserve their mutable existence; and hence life only exists on or near the surface of the earth; see Botan. Garden, Vol. I. Canto IV. l. 419. L'organisation, le sentiment, le movement spontane, la vie, n'existent qu'a la surface de la terre, et dans les lieux exposes a la lumiere. Traite de Chimie par M. Lavoisier, Tom. I. p. 202.]

"HENCE when a Monarch or a mushroom dies, Awhile extinct the organic matter lies; But, as a few short hours or years revolve, Alchemic powers the changing mass dissolve; Born to new life unnumber'd insects pant, New buds surround the microscopic plant; Whose embryon senses, and unwearied frames, Feel finer goads, and blush with purer flames; 390 Renascent joys from irritation spring, Stretch the long root, or wave the aurelian wing.

[Footnote: Born to new life, l. 387. From the innumerable births of the larger insects, and the spontaneous productions of the microscopic ones, every part of organic matter from the recrements of dead vegetable or animal bodies, on or near the surface of the earth, becomes again presently reanimated; which by increasing the number and quantity of living organizations, though many of them exist but for a short time, adds to the sum total of terrestrial happiness.]

"When thus a squadron or an army yields, And festering carnage loads the waves or fields; When few from famines or from plagues survive, Or earthquakes swallow half a realm alive;— While Nature sinks in Time's destructive storms, The wrecks of Death are but a change of forms; Emerging matter from the grave returns, Feels new desires, with new sensations burns; 400 With youth's first bloom a finer sense acquires, And Loves and Pleasures fan the rising fires.— Thus sainted PAUL, 'O Death!' exulting cries, 'Where is thy sting? O Grave! thy victories?'

[Footnote: Thus sainted Paul, l. 403. The doctrine of St. Paul teaches the resurrection of the body in an incorruptible and glorified state, with consciousness of its previous existence; he therefore justly exults over the sting of death, and the victory of the grave.]

"Immortal Happiness from realms deceased Wakes, as from sleep, unlessen'd or increased; Calls to the wise in accents loud and clear, Sooths with sweet tones the sympathetic ear; Informs and fires the revivescent clay, And lights the dawn of Life's returning day. 410

[Footnote: And lights the dawn, l. 410. The sum total of the happiness of organized nature is probably increased rather than diminished, when one large old animal dies, and is converted into many thousand young ones; which are produced or supported with their numerous progeny by the same organic matter. Linneus asserts, that three of the flies, called musca vomitoria, will consume the body of a dead horse, as soon as a lion can; Syst. Nat.]

"So when Arabia's Bird, by age oppress'd, Consumes delighted on his spicy nest; A filial Phoenix from his ashes springs, Crown'd with a star, on renovated wings; Ascends exulting from his funeral flame, And soars and shines, another and the same.

[Footnote: So when Arabia's bird, l. 411. The story of the Phoenix rising from its own ashes with a star upon its head seems to have been an hieroglyphic emblem of the destruction and resuscitation of all things; see Botan. Garden, Vol. I. Canto IV. l. 389.]

"So erst the Sage with scientific truth In Grecian temples taught the attentive youth; With ceaseless change how restless atoms pass From life to life, a transmigrating mass; 420 How the same organs, which to day compose The poisonous henbane, or the fragrant rose, May with to morrow's sun new forms compile, Frown in the Hero, in the Beauty smile. Whence drew the enlighten'd Sage the moral plan, That man should ever be the friend of man; Should eye with tenderness all living forms, His brother-emmets, and his sister-worms.

[Footnote: So erst the Sage, l. 417. It is probable, that the perpetual transmigration of matter from one body to another, of all vegetables and animals, during their lives, as well as after their deaths, was observed by Pythagoras; which he afterwards applied to the soul, or spirit of animation, and taught, that it passed from one animal to another as a punishment for evil deeds, though without consciousness of its previous existence; and from this doctrine he inculcated a system of morality and benevolence, as all creatures thus became related to each other.]

"HEAR, O ye Sons of Time! your final doom, And read the characters, that mark your tomb: 430 The marble mountain, and the sparry steep, Were built by myriad nations of the deep,— Age after age, who form'd their spiral shells, Their sea-fan gardens and their coral cells; Till central fires with unextinguished sway Raised the primeval islands into day;— The sand-fill'd strata stretch'd from pole to pole; Unmeasured beds of clay, and marl, and coal, Black ore of manganese, the zinky stone, And dusky steel on his magnetic throne, 440 In deep morass, or eminence superb, Rose from the wrecks of animal or herb; These from their elements by Life combined, Form'd by digestion, and in glands refined, Gave by their just excitement of the sense The Bliss of Being to the vital Ens.

[Footnote: The marble mountain, l. 431. From the increased knowledge in Geology during the present century, owing to the greater attention of philosophers to the situations of the different materials, which compose the strata of the earth, as well as to their chemical properties, it seems clearly to appear, that the nucleus of the globe beneath the ocean consisted of granite; and that on this the great beds of limestone were formed from the shells of marine animals during the innumerable primeval ages of the world; and that whatever strata lie on these beds of limestone, or on the granite, where the limestone does not cover it, were formed after the elevation of islands and continents above the surface of the sea by the recrements of vegetables and of terrestrial animals; see on this subject Botanic Garden, Vol. I. Additional Note XXIV.]

"Thus the tall mountains, that emboss the lands, Huge isles of rock, and continents of sands, Whose dim extent eludes the inquiring sight, ARE MIGHTY MONUMENTS OF PAST DELIGHT; 450 Shout round the globe, how Reproduction strives With vanquish'd Death,—and Happiness survives; How Life increasing peoples every clime, And young renascent Nature conquers Time; —And high in golden characters record The immense munificence of NATURE'S LORD!—

[Footnote: Are mighty monuments, l. 450. The reader is referred to a few pages on this subject in Phytologia, Sect. XIX. 7. 1, where the felicity of organic life is considered more at large; but it is probable that the most certain way to estimate the happiness and misery of organic beings; as it depends on the actions of the organs of sense, which constitute ideas; or of the muscular fibres which perform locomotion; would be to consider those actions, as they are produced or excited by the four sensorial powers of irritation, sensation, volition, and association. A small volume on this subject by some ingenious writer, might not only amuse, as an object of curiosity; but by showing the world the immediate sources of their pains and pleasures might teach the means to avoid the one, and to procure the other, and thus contribute both ways to increase the sum total of organic happiness.]

[Footnote: How Life increasing, l. 453. Not only the vast calcareous provinces, which form so great a part of the terraqueous globe, and also whatever rests upon them, as clay, marl, sand, and coal, were formed from the fluid elements of heat, oxygen, azote, and hydrogen along with carbon, phosphorus, and perhaps a few other substances, which the science of chemistry has not yet decomposed; and gave the pleasure of life to the animals and vegetables, which formed them; and thus constitute monuments of the past happiness of those organized beings. But as those remains of former life are not again totally decomposed, or converted into their original elements, they supply more copious food to the succession of new animal or vegetable beings on their surface; which consists of materials convertible into nutriment with less labour or activity of the digestive powers; and hence the quantity or number of organized bodies, and their improvement in size, as well as their happiness, has been continually increasing, along with the solid parts of the globe; and will probably continue to increase, till the whole terraqueous sphere, and all that inhabit it shall dissolve by a general conflagration, and be again reduced to their elements.

Thus all the suns, and the planets, which circle round them, may again sink into one central chaos; and may again by explosions produce a new world; which in process of time may resemble the present one, and at length again undergo the same catastrophe! these great events may be the result of the immutable laws impressed on matter by the Great Cause of Causes, Parent of Parents, Ens Entium!]

"He gives and guides the sun's attractive force, And steers the planets in their silver course; With heat and light revives the golden day, And breathes his spirit on organic clay; 460 With hand unseen directs the general cause By firm immutable immortal laws."

Charm'd with her words the Muse astonish'd stands, The Nymphs enraptured clasp their velvet hands; Applausive thunder from the fane recoils, And holy echoes peal along the ailes; O'er NATURE'S shrine celestial lustres glow, And lambent glories circle round her brow.

IV. Now sinks the golden sun,—the vesper song Demands the tribute of URANIA'S tongue; 470 Onward she steps, her fair associates calls From leaf-wove avenues, and vaulted halls. Fair virgin trains in bright procession move, Trail their long robes, and whiten all the grove; Pair after pair to Nature's temple sweep, Thread the broad arch, ascend the winding steep; Through brazen gates along susurrant ailes Stream round their GODDESS the successive files; Curve above curve to golden seats retire, And star with beauty the refulgent quire. 480

AND first to HEAVEN the consecrated throng With chant alternate pour the adoring song, Swell the full hymn, now high, and now profound, With sweet responsive symphony of sound. Seen through their wiry harps, below, above, Nods the fair brow, the twinkling fingers move; Soft-warbling flutes the ruby lip commands, And cymbals ring with high uplifted hands.

TO CHAOS next the notes melodious pass, How suns exploded from the kindling mass, 490 Waved o'er the vast inane their tresses bright, And charm'd young Nature's opening eyes with light. Next from each sun how spheres reluctant burst, And second planets issued from the first. And then to EARTH descends the moral strain, How isles, emerging from the shoreless main, With sparkling streams and fruitful groves began, And form'd a Paradise for mortal man.

[Footnote: To Chaos next, l. 489.

Namque canebat uti magnum per inane coacta Semina terrarumque, animaeque, marisque fuissent; Et liquidi simul ignis; ut his exordia primis Omnia, et ipse tener mundi concreverit orbis. VIRG. EC. VI. l. 31.]

Sublimer notes record CELESTIAL LOVE, And high rewards in brighter climes above; 500 How Virtue's beams with mental charm engage Youth's raptured eye, and warm the frost of age, Gild with soft lustre Death's tremendous gloom, And light the dreary chambers of the tomb. How fell Remorse shall strike with venom'd dart, Though mail'd in adamant, the guilty heart; Fierce furies drag to pains and realms unknown The blood-stain'd tyrant from his tottering throne.

By hands unseen are struck aerial wires, And Angel-tongues are heard amid the quires; 510 From aile to aile the trembling concord floats, And the wide roof returns the mingled notes, Through each fine nerve the keen vibrations dart, Pierce the charm'd ear, and thrill the echoing heart.—

MUTE the sweet voice, and still the quivering strings, Now Silence hovers on unmoving wings.— —Slow to the altar fair URANIA bends Her graceful march, the sacred steps ascends, High in the midst with blazing censer stands, And scatters incense with illumined hands: 520 Thrice to the GODDESS bows with solemn pause, With trembling awe the mystic veil withdraws, And, meekly kneeling on the gorgeous shrine, Lifts her ecstatic eyes to TRUTH DIVINE! 524





36 Origin of European Nations. 76 Early use of Painting and Hieroglyphics. 83 Proteus represents Time. 126 Cave of Trophonius. 137 Eleusinian Mysteries. 176 Antiquity of Statuary, casting Figures, and Carving. 224 Infancy of the present World. 235 Of Heat. 239 Of Attraction. 245 Of Contraction. 259 Arteries not conical. 262 Venous Absorption. 268 Decrease of the Ocean. 270 Sensation and Volition. 283 Mucor, Vibrio. 295 Animals are first aquatic. 315 Sea, originally was not Salt. 327 Animals from the Sea. 335 Aquatic Plants. 343 Frogs. 363 Rainbow in Northern Latitudes. 372 Venus rising from the Sea. 392 The Fetus in the Womb. 417 Animals from the Mud of the Nile.


1 Shortness of Life. 3 Old Age surprising. 39 Organic and chemical Properties. 43 Immortality of Matter. 47 Adonis emblem of Life. 71 The Truffle, Lycoperdon. 83 Volvox. 85 Polypus. 87 Taenia. 89 Oysters. 90 Coral-Insect. 114 Female Sex produced. 118 Power of Imagination. 122 Mankind were formerly Hermaphrodites and Quadrupeds. 167 Hereditary Diseases of Vegetables. 223 Psyche and Cupid. 268 Some Honey poisonous. 271 Appetency and Propensity. 280 Vallisneria. 288 Lampyris. 302 Insects from Anthers and Stigmas. 321 Horns of Stags, and Tusks of Boars, Spurs of Cocks. 351 Chick in the Egg. 356 Songs of Birds. 373 How Fish swim. 375 How Birds fly. 434 Of Smiles, and of Laughter.


13 Oxygen, and Hydrogen, and Azote. 21 Two electric Ethers. 64 Irritation. 72 Sensation. 73 Volition, Memory. 81 Intuitive Analogy. 91 Association. 103 Armour of Brutes. 122 Of the Human Hand. 125 Perception of Figure. 144 Sight the Language of the Touch. 145 Surprise, Novelty, Curiosity. 152 The Lips an Organ of Touch. 176 Ideal Beauty. 178 Two Deities of Love. 207 Idea of Beauty from the Female Bosom. 230 Taste for Sublimity. 237 Poetic Melancholy. 246 Taste for Tragedy. 258 Taste for uncultivated Nature. 270 Accumulation of sensorial Power. 294 Imitation described. 303 Imitation of one Sense by another. 319 Mimickry or Resemblance. 334 The Parts of the System imitate each other. 342 External Signs of Passions. 371 Theory of Language. 398 Ideas so called are parts of a train of Actions. 401 Of Reason. 411 Reasoning of Insects. 435 Volition distinguishes Mankind. 456 If Knowledge produces Happiness. 466 Sympathy the source of Virtue. 485 Maxim of Socrates.


29 Oestrus or Gadfly. 33 Ichneumon fly. 37 Libellula. 39 Bees. 57 Shark. 59 Crocodile 66 Animals prey on Vegetables. 71 Defect of Stimulus. 87 Theatric Preachers. 93 Pleasure of Life, Ennui. 94 Of Tooth-edge. 119 Epidemic Complaints. 130 Compassion may be too great. 147 Doctrine of Atoms. 160 Pleasure of viewing a Landscape. 178 Pleasure from Music. 242 Ancient Orators spoke disrespectfully of the mechanic Philosophers. 270 Influence of Printing. 299 Associated ideas of three Classes. 309 Wit defined. 349 Surprising number of Seeds. 351 Of the Aphis, its Numbers. 352 Aphis drinks the Sap-juice. 359 The Mutation of the Tadpole. 387 Animation near the Surface of the Earth. 387 All dead animal and vegetable Bodies become animated. 403 Doctrine of St. Paul. 411 Happiness increased. 417 Doctrine of Pythagoras. 431 Geology. 450 Method of investigation of Organic happiness. 453 Organic Life increases.




Hence without parent by spontaneous birth Rise the first specks of animated earth. CANTO I. l. 227.

Prejudices against this doctrine.

I. From the misconception of the ignorant or superstitious, it has been thought somewhat profane to speak in favour of spontaneous vital production, as if it contradicted holy writ; which says, that God created animals and vegetables. They do not recollect that God created all things which exist, and that these have been from the beginning in a perpetual state of improvement; which appears from the globe itself, as well as from the animals and vegetables, which possess it. And lastly, that there is more dignity in our idea of the supreme author of all things, when we conceive him to be the cause of causes, than the cause simply of the events, which we see; if there can be any difference in infinity of power!

Another prejudice which has prevailed against the spontaneous production of vitality, seems to have arisen from the misrepresentation of this doctrine, as if the larger animals had been thus produced; as Ovid supposes after the deluge of Deucalion, that lions were seen rising out of the mud of the Nile, and struggling to disentangle their hinder parts. It was not considered, that animals and vegetables have been perpetually improving by reproduction; and that spontaneous vitality was only to be looked for in the simplest organic beings, as in the smallest microscopic animalcules; which perpetually, perhaps hourly, enlarge themselves by reproduction, like the roots of tulips from seed, or the buds of seedling trees, which die annually, leaving others by solitary reproduction rather more perfect than themselves for many successive years, till at length they acquire sexual organs or flowers.

A third prejudice against the existence of spontaneous vital productions has been the supposed want of analogy; this has also arisen from the expectation, that the larger or more complicated animals should be thus produced; which have acquired their present perfection by successive generations during an uncounted series of ages. Add to this, that the want of analogy opposes the credibility of all new discoveries, as of the magnetic needle, and coated electric jar, and Galvanic pile; which should therefore certainly be well weighed and nicely investigated before distinct credence is given them; but then the want of analogy must at length yield to repeated ocular demonstration.

Preliminary observations.

II. Concerning the spontaneous production of the smallest microscopic animals it should be first observed, that the power of reproduction distinguishes organic being, whether vegetable or animal, from inanimate nature. The circulation of fluids in vessels may exist in hydraulic machines, but the power of reproduction belongs alone to life. This reproduction of plants and of animals is of two kinds, which may be termed solitary and sexual. The former of these, as in the reproduction of the buds of trees, and of the bulbs of tulips, and of the polypus, and aphis, appears to be the first or most simple mode of generation, as many of these organic beings afterwards acquire sexual organs, as the flowers of seedling trees, and of seedling tulips, and the autumnal progeny of the aphis. See Phytologia.

Secondly, it should be observed, that by reproduction organic beings are gradually enlarged and improved; which may perhaps more rapidly and uniformly occur in the simplest modes of animated being; but occasionally also in the more complicated and perfect kinds. Thus the buds of a seedling tree, or the bulbs of seedling tulips, become larger and stronger in the second year than the first, and thus improve till they acquire flowers or sexes; and the aphis, I believe, increases in bulk to the eighth or ninth generation, and then produces a sexual progeny. Hence the existence of spontaneous vitality is only to be expected to be found in the simplest modes of animation, as the complex ones have been formed by many successive reproductions.

Experimental facts.

III. By the experiments of Buffon, Reaumur, Ellis, Ingenhouz, and others, microscopic animals are produced in three or four days, according to the warmth of the season, in the infusions of all vegetable or animal matter. One or more of these gentlemen put some boiling veal broth into a phial previously heated in the fire, and sealing it up hermetically or with melted wax, observed it to be replete with animalcules in three or four days.

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.

M. Girtanner asserts, that this green vegetable matter is not produced by water and heat alone, 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.

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 the other, and the latter a propensity to be united with the former; and they are probably separated 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 restoration 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 previously 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.

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 length, contract themselves by their elasticity, like an animal fibre by stimulus. The laws of action of these, and all other elastic bodies, are not yet understood; as the laws of the attraction of cohesion, to produce these effects, must be very different from those of general attraction, since the farther the particles of elastic bodies are drawn from each other till they separate, the stronger they seem to attract; and the nearer they are pressed together, the more they seem to repel; as in bending a spring, or in extending a piece of elastic gum; which is the reverse to what occurs in the attractions of disunited bodies; and much wants further investigation. So the spontaneous production 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 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 Linnaeus dwells in vinegar and in bookbinders 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 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 Encyclopedia, Art. Animalcule.

Thus some shell-snails in the cabinets of the curious have been kept in a dry state for ten 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, regain some degree of vitality, since this is done by more complicate animal organs in the instances above mentioned.

The hydra of Linnaeus, 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.

To this should be added, that these microscopic animals are found in all solutions of vegetable or animal matter in water; as black pepper steeped in water, hay suffered to become putrid in water, and the water of dunghills, afford animalcules in astonishing numbers. See Mr. Ellis's curious account of Animalcules produced from an infusion of Potatoes and Hempseed; Philos. Transact. Vol. LIX. from all which it would appear, that organic particles of dead vegetables and animals during their usual chemical changes into putridity or acidity, do not lose all their organization or vitality, but retain so much of it as to unite with the parts of living animals in the process of nutrition, or unite and produce new complicate animals by secretion as in generation, or produce very simple microscopic animals or microscopic vegetables, by their new combinations in warmth and moisture.

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.


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 gardeners; Kennedy on Gardening.


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: Sphaericum. Spherical. 4. Enchelis: Cylindracea. Cylindrical. 5. Vibrio: Elongatum. Long.


6. Cyclidium: Ovale. Oval. 7. Paramecium: Oblongum. Oblong. 8. Kolpoda: Sinuatum. Sinuous. 9. Gonium: Angulatum. With angles. 10. Bursaria. Hollow like a purse.

II. Those that have External Organs.

*Naked, or not enclosed in a shell.

1. Cercaria: Caudatum. With a tail. 2. Trichoda: Crinitum. Hairy. 3. Kerona: Corniculatum. With horns. 4. Himantopus: Cirratum. Cirrated. 5. Leucophra: Ciliatum undique. Every part ciliated. 6. Vorticella: Ciliatum apice. The apex ciliated.

*Covered with a shell.

7. Brachionus: Ciliatum apice. The apex ciliated.

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.

4. Those animalcules discovered in pustules of the itch, in the feces of dysenteric patients, and in semine masculino, I suppose to be produced by the stagnation and incipient decomposition of those materials in their receptacles, and 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 evaporated, they are seen to flock towards the remaining 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.



Next the long nerves unite their silver train, And young Sensation permeates the brain. CANT. I. l. 250.

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.

VIII. These four faculties of the sensorium during their inactive state are termed irritability, sensibility, voluntarily, and associability; in their active state they are termed as above irritation, sensation, volition, association.

Irritation is an exertion or change of some extreme part of the sensorium residing in the muscles or organs of sense, in consequence of the appulses of external bodies.

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.


Next when imprison'd fires in central caves Burst the firm earth, and drank the headlong waves. CANTO I. l. 302.

The great and repeated explosions of volcanoes are shown by Mr. Mitchell in the Philosoph. Transact. 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 intire, 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.

Mr. Mitchell observes, that the agitations of the earth from the great earthquake at Lisbon 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 subterraneous fires at some great depth beneath those parts of this island; see on this subject Botanic Garden, Vol. II. Canto IV. l. 79, note. For an account of the noxious vapours emitted from volcanoes, see Botanic Garden, Vol. II. Cant. IV. l. 328, note. For the milder effects of central fires, see Botanic Garden, Vol. I. Cant. I. l. 139, and Additional Note VI.


So from deep lakes the dread musquito springs, Drinks the soft breeze, and dries his tender wings. CANTO I. l. 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 antennae 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 fly-state 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 institute 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 larvae of which exist in the bodies of cattle, where they are nourished during the winter, and are occasionally extracted by a bird of the crow-kind called buphaga. These larvae 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 tube; of the musca chamaeleon, the larva lives in fountains, and the fly occasionally walks upon the water. The musca vomitoria is produced in carcases; three of these flies consume the dead body of a horse as soon as a lion. Lin. Syst. Nat.



So still the Diodons, amphibious tribe, With twofold lungs the sea and air imbibe. CANT. I. l. 331.

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.

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 to 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 one-celled 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 gills had power to decompose the water and obtain the oxygen from it.

The lamprey, petromyzon, is put by Linneus amongst 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.



So erst as Egypt's rude designs explain. CANTO I. l. 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 of an evil demon; to which may be added the cap of liberty and the tiara of popedom. It is to be wished that many other universal characters could be introduced into practice, which might either constitute a more comprehensive language for painters, or for other arts; as those of ciphers and signs have done for arithmetic and algebra, and crotchets for music, and the alphabets for articulate sounds; so a zigzag line made on white paper by a black-lead pencil, which communicates with the surface of the mercury in the barometer, as the paper itself is made constantly to move laterally by a clock, and daily to descend through the space necessary, has ingeniously produced a most accurate visible account of the rise and fall of the mercury in the barometer every hour in the year.

Mr. Grey's Memoria Technica was designed as an artificial language to remember numbers, as of the eras, or dates of history. This was done by substituting one consonant and one vowel for each figure of the ten cyphers used in arithmetic, and by composing words of these letters; which words Mr. Grey makes into hexameter verses, and produces an audible jargon, which is to be committed to memory, and occasionally analysed into numbers when required. An ingenious French botanist, Monsieur Bergeret, has proposed to apply this idea of Mr. Grey to a botanical nomenclature, by making the name of each plant to consist of letters, which, when analysed, were to signify the number of the class, order, genus, and species, with a description also of some particular part of the plant, which was designed to be both an audible and visible language.

Bishop Wilkins in his elaborate "Essay towards a Real Character and a Philosophical Language," has endeavoured to produce, with the greatest simplicity, and accuracy, and conciseness, an universal language both to be written and spoken, for the purpose of the communication of all our ideas with greater exactness and less labour than is done in common languages, as they are now spoken and written. But we have to lament that the progress of general science is yet too limited both for his purpose, and for that even of a nomenclature for botany; and that the science of grammar, and even the number and manner of the pronunciation of the letters of the alphabet, are not yet determined with such accuracy as would be necessary to constitute Bishop Wilkins's grand design of an universal language, which might facilitate the acquirement of knowledge, and thus add to the power and happiness of mankind.



The age-worn fibres goaded to contract By repetition palsied, cease to act. CANTO II. l. 4

I. Effects of Age.

The immediate cause of the infirmities of age, or of the progress of life to death, has not yet been well ascertained. The answer to the question, why animals become feeble and diseased after a time, though nourished with the same food which increased their growth from infancy, and afterwards supported them for many years in unimpaired health and strength, must be sought for from the laws of animal excitability, which, though at first increased, is afterwards diminished by frequent repetitions of its adapted stimulus, and at length ceases to obey it.

1. There are four kinds of stimulus which induce the fibres to contract, which constitute the muscles or the organs of sense; as, first, The application of external bodies, which excites into action the sensorial power of irritation; 2dly, Pleasure and pain, which excite into action the sensorial power of sensation; 3dly, Desire and aversion, which excite into action the power of volition; and lastly, The fibrous contractions, which precede association, which is another sensorial power; see Zoonomia, Vol. I. Sect. II. 13.

Many of the motions of the organic system, which are necessary to life, are excited by more than one of these stimuli at the same time, and some of them occasionally by them all. Thus respiration is generally caused by the stimulus of blood in the lungs, or by the sensation of the want of oxygen; but is also occasionally voluntary. The actions of the heart also, though generally owing to the stimulus of the blood, are also inflamed by the association of its motions with those of the stomach, whence sometimes arises an inequality of the pulse, and with other parts of the system, as with the capillaries, whence heat of the skin in fevers with a feeble pulse, see Zoonomia. They are also occasionally influenced by sensation, as is seen in the paleness occasioned by fear, or the blush of shame and anger; and lastly the motions of the heart are sometimes assisted by volition; thus in those who are much weakened by fevers, the pulse is liable to stop during their sleep, and to induce great distress; which is owing at that time to the total suspension of voluntary power; the same occurs during sleep in some asthmatic patients.

2. The debility of approaching age appears to be induced by the inactivity of many parts of the system, or their disobedience to their usual kinds and quantities of stimulus: thus the pallid appearance of the skin of old age is owing to the inactivity of the heart, which ceases to obey the irritation caused by the stimulus of the blood, or its association with other moving organs with its former energy; whence the capillary arteries are not sufficiently distended in their diastole, and consequently contract by their elasticity, so as to close the canal, and their sides gradually coalesce. Of these, those which are most distant from the heart, and of the smallest diameters, will soonest close, and become impervious; hence the hard pulse of aged patients is occasioned by the coalescence of the sides of the vasa vasorum, or capillary arteries of the coats of the other arteries.

The veins of elderly people become turgid or distended with blood, and stand prominent on the skin; for as these do not possess the elasticity of the arteries, they become distended with accumulation of blood; when the heart by its lessened excitability does not contract sufficiently forcibly, or frequently, to receive, as fast as usual, the returning blood; and their apparent prominence on the skin is occasioned by the deficient secretion of fat or mucus in the cellular membrane; and also to the contraction and coalescence and consequent less bulk of many capillary arteries.

3. Not only the muscular fibres lose their degree of excitability from age, as in the above examples; and as may be observed in the tremulous hands and feeble step of elderly persons; but the organs of sense become less excitable by the stimulus of external objects; whence the sight and hearing become defective; the stimulus of the sensorial power of sensation also less affects the aged, who grieve less for the loss of friends or for other disappointments; it should nevertheless be observed, that when the sensorial power of irritation is much exhausted, or its production much diminished; the sensorial power of sensation appears for a time to be increased; as in intoxication there exists a kind of delirium and quick flow of ideas, and yet the person becomes so weak as to totter as he walks; but this delirium is owing to the defect of voluntary power to correct the streams of ideas by intuitive analogy, as in dreams: see Zoonomia: and thus also those who are enfeebled by habits of much vinous potation, or even by age alone, are liable to weep at shaking hands with a friend, whom they have not lately seen; which is owing to defect of voluntary power to correct their trains of ideas caused by sensation, and not to the increased quantity of sensation, as I formerly supposed.

The same want of voluntary power to keep the trains of sensitive ideas consistent, and to compare them by intuitive analogy with the order of nature, is the occasion of the starting at the clapping to of a door, or the fall of a key, which occasions violent surprise with fear and sometimes convulsions, in very feeble hysterical patients, and is not owing I believe (as I formerly supposed) to increased sensation; as they are less sensible to small stimuli than when in health.

Old people are less able also to perform the voluntary exertions of exercise or of reasoning, and lastly the association of their ideas becomes more imperfect, as they are forgetful of the names of persons and places; the associations of which are less permanent, than those of the other words of a language, which are more frequently repeated.

4. This disobedience of the fibres of age to their usual stimuli, has generally been ascribed to repetition or habit, as those who live near a large clock, or a mill, or a waterfall, soon cease to attend to the perpetual noise of it in the day, and sleep dining the night undisturbed. Thus all medicines, if repeated too frequently, gradually lose their effect; as wine and opium cease to intoxicate: some disagreeable tastes as tobacco, by frequent repetition cease to be disagreeable; grief and pain gradually diminish and at length cease altogether; and hence life itself becomes tolerable.

This diminished power of contraction of the fibres of the muscles or organs of sense, which constitutes permanent debility or old age, may arise from a deficient secretion of sensorial power in the brain, as well as from the disobedience of the muscles and organs of sense to their usual stimuli; but this less production of sensorial power must depend on the inactivity of the glands, which compose the brain, and are believed to separate it perpetually from the blood; and is thence owing to a similar cause with the inaction of the fibres of the other parts of the system.

It is finally easy to understand how the fibres may cease to act by the usual quantity of stimulus after having been previously exposed to a greater quantity of stimulus, or to one too long continued; because the expenditure of sensorial power has then been greater than its production; but it is not easy to explain why the repetition of fibrous contractions, which during the meridian of life did not expend the sensorial power faster than it was produced; or only in such a degree as was daily restored by rest and sleep, should at length in the advance of life expend too much of it; or otherwise, that less of it should be produced in the brain; or reside in the nerves; lastly that the fibres should become less excitable by the usual quantity of it.

5. But these facts would seem to show, that all parts of the system are not changed as we advance in life, as some have supposed; as in that case it might have preserved for ever its excitability; and it might then perhaps have been easier for nature to have continued her animals and vegetables for ever in their mature state, than perpetually by a complicate apparatus to have produced new ones, and suffer the old ones to perish; for a further account of stimulus and the consequent animal exertion, see Zoonomia, Vol. I. Sect. 12.

II. Means of preventing old age.

The means of preventing the approach of age must therefore consist in preventing the inexcitability of the fibres, or the diminution of the production of sensorial power.

1. As animal motion cannot be performed without the fluid matter of heat, in which all things are immersed, and without a sufficient quantity of moisture to prevent rigidity: nothing seems so well adapted to both these purposes as the use of the warm bath; and especially in those, who become thin or emaciated with age, and who have a hard and dry skin, with hardness of the coat of the arteries; which feels under the finger like a cord; the patient should sit in warm water for half an hour every day, or alternate days, or twice a week; the heat should be about ninety-eight degrees on Fahrenheit's scale, or of such a warmth, as may be most agreeable to his sensation; but on leaving the bath he should always be kept so cool, whether he goes into bed, or continues up, as not sensibly to perspire.

There is a popular prejudice, that the warm bath relaxes people, and that the cold bath braces them; which are mechanical terms belonging to drums and fiddle-strings, but not applicable except metaphorically to animal bodies, and then commonly mean weakness and strength: during the continuance in the bath the patient does not lose weight, unless he goes in after a full meal, but generally weighs heavier as the absorption is greater than the perspiration; but if he suffers himself to sweat on his leaving the bath, he will undoubtedly be weakened by the increased action of the system, and its exhaustion: the same occurs to those who are heated by exercise, or by wine, or spice, but not during their continuance in the warm bath: whence we may conclude, that the warm bath is the most harmless of all those stimuli, which are greater than our natural habits have accustomed us to; and that it particularly counteracts the approach of old age in emaciated people with dry skins.

It may be here observed in favour of bathing, that some fish are believed to continue to a great age, and continually to enlarge in size, as they advance in life; and that long after their state of puberty. I have seen perch full of spawn, which were less than two inches long; and it is known, that they will grow to six or eight times that size; it is said, that the whales, which have been caught of late years, are much less in size than those, which were caught, when first the whale-fishery was established; as the large ones, which were supposed to have been some hundred years old, are believed to be already destroyed.

All cold-blooded amphibious animals more slowly waste their sensorial power; as they are accustomed to less stimulus from their respiring less oxygen; and their movements in water are slower than those of aerial animals from the greater resistance of the element. There besides seems to be no obstacle to the growth of aquatic animals; as by means of the air-bladder, they can make their specific gravity the same as that of the water in which they swim. And the moisture of the element seems well adapted to counteract the rigidity of their fibres; and as their exertions in locomotion, and the pressure of some parts on others, are so much less than in the bodies of land animals.

2. But as all excessive stimuli exhaust the sensorial power, and render the system less excitable for a time till the quantity of sensorial power is restored by sleep, or by the diminution or absence of stimulus; which is seen by the weakness of inebriates for a day at least after intoxication. And as the frequent repetition of this great and unnatural stimulus of fermented liquors produces a permanent debility, or disobedience of the system to the usual and natural kinds and quantities of stimulus, as occurs in those who have long been addicted to the ingurgitation of fermented liquors.

And as, secondly, the too great deficiency of the quantity of natural stimuli, as of food, and warmth, or of fresh air, produces also diseases; as is often seen in the children of the poor in large towns, who become scrofulous from want of due nourishment, and from cold, damp, unairy lodgings.

The great and principal means to prevent the approach of old age and death, must consist in the due management of the quantity of every kind of stimulus, but particularly of that from objects external to the moving organ; which may excite into action too great or too small a quantity of the sensorial power of irritation, which principally actuates the vital organs. Whence the use of much wine, or opium, or spice, or of much salt, by their unnatural stimulus induces consequent debility, and shortens life, on the one hand, by the exhaustion of sensorial power; so on the other hand, the want of heat, food, and fresh air, induces debility from defect of stimulus, and a consequent accumulation of sensorial power, and a general debility of the system. Whence arise the pains of cold and hunger, and those which are called nervous; and which are the cause of hysteric, epileptic, and perhaps of asthmatic paroxysms, and of the cold fits of fever.

3. Though all excesses of increase and decrease of stimulus should be avoided, yet a certain variation of stimulus seems to prolong the excitability of the system; as during any diminution of the usual quantity of stimulus, an accumulation of sensorial power is produced; and in consequence the excitability, which was lessened by the action of habitual stimulus, becomes restored. Thus those, who are uniformly habituated to much artificial heat, as in warm parlours in the winter months, lose their irritability in some degree, and become feeble like hot-house plants; but by frequently going for a time into the cold air, the sensorial power of irritability is accumulated and they become stronger.

Whence it may be deduced, that the variations of the cold and heat of this climate contribute to strengthen its inhabitants, who are more active and vigorous, and live longer, than those of either much warmer or much colder latitudes.

This accumulation of sensorial power from diminution of stimulus any one may observe, who in severe weather may sit by the fire-side till he is chill and uneasy with the sensation of cold; but if he walks into the frosty air for a few minutes, an accumulation of sensorial power is produced by diminution of the stimulus of heat, and on his returning into the room where he was chill before, his whole skin will now glow with warmth.

Hence it may be concluded, that the variations of the quantity of stimuli within certain limits contribute to our health; and that those houses which are kept too uniformly warm, are less wholesome than where the inhabitants are occasionally exposed to cold air in passing from one room to another.

Nevertheless to those weak habits with pale skins and large pupils of the eyes, whose degree of irritability is less than health requires, as in scrofulous, hysterical, and some consumptive constitutions, a climate warmer than our own may be of service, as a greater stimulus of heat may be wanted to excite their less irritability. And also a more uniform quantity of heat may be serviceable to consumptive patients than is met with in this country, as the lungs cannot be clothed like the external skin, and are therefore subject to greater extremes of heat and cold in passing in winter from a warm room into the frosty air.

4. It should nevertheless be observed, that there is one kind of stimulus, which though it be employed in quantity beyond its usual state, seems to increase the production of sensorial power beyond the expenditure of it (unless its excess is great indeed) and thence to give permanent strength and energy to the system; I mean that of volition. This appears not only from the temporary strength of angry or insane people, but because insanity even cures some diseases of debility, as I have seen in dropsy, and in some fevers; but it is also observable, that many who have exerted much voluntary effort during their whole lives, have continued active to great age. This however may be conceived to arise from these great exertions being performed principally by the organs of sense, that is by exciting and comparing ideas; as in those who have invented sciences, or have governed nations, and which did not therefore exhaust the sensorial power of those organs which are necessary to life, but perhaps rather prevented them from being sooner impaired, their sensorial power not having been so frequently exhausted by great activity, for very violent exercise of the body, long continued, forwards old age; as is seen in post-horses that are cruelly treated, and in many of the poor, who with difficulty support their families by incessant labour.

III. Theory of the Approach of Age.

The critical reader is perhaps by this time become so far interested in this subject as to excuse a more prolix elucidation of it.

In early life the repetition of animal actions occasions them to be performed with greater facility, whether those repetitions are produced by volition, sensation, or irritation; because they soon become associated together, if as much sensorial power is produced between every reiteration of action, as is expended by it.

But if a stimulus be repeated at uniform intervals of time, the action, whether of our muscles or organs of sense, is performed with still greater facility and energy; because the sensorial power of association mentioned above, is combined with the sensorial power of irritation, and forms part of the diurnal chain of animal motions; that is, in common language, the acquired habit assists the power of the stimulus; see Zoonomia, Vol. I. Sect. XXII. 2. and Sect. XII. 3. 3.

On this circumstance depends the easy motions of the fingers in performing music, and of the feet and arms in dancing and fencing, and of the hands in the use of tools in mechanic arts, as well as all the vital motions which animate and nourish organic bodies.

On the contrary, many animal motions by perpetual repetition are performed with less energy; as those who live near a waterfall, or a smith's forge, after a time, cease to hear them. And in those infectious diseases which are attended with fever, as the small-pox and measles, violent motions of the system are excited, which at length cease, and cannot again be produced by application of the same stimulating material; as when those are inoculated for the small-pox, who have before undergone that malady. Hence the repetition, which occasions animal actions for a time to be performed with greater energy, occasions them at length to become feeble, or to cease entirely.

To explain this difficult problem we must more minutely consider the catenations of animal motions, as described in Zoonomia, Vol. I. Sect. XVII. The vital motions, as suppose of the heart and arterial system, commence from the irritation occasioned by the stimulus of the blood, and then have this irritation assisted by the power of association; at the same time an agreeable sensation is produced by the due actions of the fibres, as in the secretions of the glands, which constitutes the pleasure of existence; this agreeable sensation is intermixed between every link of this diurnal chain of actions, and contributes to produce it by what is termed animal causation. But there is also a degree of the power of volition excited in consequence of this vital pleasure, which is also intermixed between the links of the chain of fibrous actions; and thus also contributes to its uniform easy and perpetual production.

The effects of surprise and novelty must now be considered by the patient reader, as they affect the catenations of action; and, I hope, the curiosity of the subject will excuse the prolixity of this account of it. When any violent stimulus breaks the passing current or catenation of our ideas, surprise is produced, which is accompanied with pain or pleasure, and consequent volition to examine the object of it, as explained in Zoonomia, Vol. I. Sect. XVIII. 17, and which never affects us in sleep. In our waking hours whenever an idea of imagination occurs, which is incongruous to our former experience, we feel another kind of surprise, and instantly dissever the train of imagination by the power of volition, and compare the incongruous idea with our previous knowledge of nature, and reject it by an act of reasoning, of which we are unconscious, termed in Zoonomia, "Intuitive Analogy," Vol. I Sect. XVII. 7.

The novelty of any idea may be considered as affecting us with another kind of surprise, or incongruity, as it differs from the usual train of our ideas, and forms a new link in this perpetual chain; which, as it thus differs from the ordinary course of nature, we instantly examine by the voluntary efforts of intuitive analogy; or by reasoning, which we attend to; and compare it with the usual appearances of nature.

These ideas which affect us with surprise, or incongruity, or novelty, are attended with painful or pleasurable sensation; which we mentioned before as intermixing with all catenations of animal actions, and contributing to strengthen their perpetual and energetic production; and also exciting in some degree the power of volition, which also intermixes with the links of the chain of animal actions, and contributes to produce it.

Now by frequent repetition the surprise, incongruity, or novelty ceases; and, in consequence, the pleasure or pain which accompanied it, and also the degree of volition which was excited by that sensation of pain or pleasure; and thus the sensorial power of sensation and of volition are subducted from the catenation of vital actions, and they are in consequence produced much weaker, and at length cease entirely. Whence we learn why contagious matters induce their effects on the circulation but once; and why, in process of time, the vital movements are performed with less energy, and at length cease; whence the debilities of age, and consequent death.



But Reproduction with ethereal fires New life rekindles, ere the first expires. CANTO II. l. 13.

I. The reproduction or generation of living organized bodies, is the great criterion or characteristic which distinguishes animation from mechanism. Fluids may circulate in hydraulic machines, or simply move in them, as mercury in the barometer or thermometer, but the power of producing an embryon which shall gradually acquire similitude to its parent, distinguishes artificial from natural organization.

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