customed, will any one demonstrate, that accommmodating nature does not here as in the puceron adopt a new method to accomplish her designs? In all living bodies, it frequently happens that several characteristic distinctions, as the colour, the features, and a number of diseases that are originally the effects of circumstance, do at last become so fixed in the system, that they are afterwards transmitted to posterity through some generations. With regard to animals these facts are well known; and as to vegetables, it has been observed by pupil of Linnéus, that the apple-trees which are sent from Britain to New England blossom at first too carly for the climate, and bear no fruit; and that it is only after some years that they conform to their situation: and this circumstance, by the way, explains why roots and seeds germinate sooner when brought from southern than when they are brought from northern latitudes. The very permanency of these effects has often been the cause of much confusion and error in philosophy: for the naturalist, mistaking the lasting though temporary qualities of habit for the real and essential qualities of species, has not unfrequently drawn conclusions from his experiments that have been contradicted by similar experiments in other circumstances. This is one of the obvious reasons why experiments exhibit so many inconsistencies and contradictions, and why we are amused with such a multitude of visionary theories about the properties of living bodies.

From not attending to the numerous circumstances that induce habits, and to that general accommodating principle in living bodies, many medical prescriptions are found to be not only useless but mischievous; and many parents, by studying the health and comfort of their children, bring on habits that prove the sources of perpetual sickness, or the certain presages of an early death.

The accommodating principle is one of the consequences of irritability. Its various effects arise from the actions of different stimulants on the irritable fibre; and the after-duration of these effects, from the modifications of the irritable fibre, become habitual from the frequently repeated action of the stimulants.

The design of this accomodating principle is to fit both the plant and the animal for a more extensive and a more varied range of existence.

More remarkably striking however than any of those changes to which the plant and animal are exposed, from the variations of habit or the change of integuments, are those alterations which they undergo from metamorphosis or transformation. It has indeed been asserted, that these alterations consist in throwing off certain temporary coverings or envelops: but there is here a want of precision in the ideas, and consequently a want of accuracy in the expression. The same persons who make this assertion inform us, that caterpillars change their skin, and many of them even several times, previous to the period of their transformation. Transformation, therefore, and a change of integu. ments by their own concessions, are different things. The truth is, transformation frequently takes place independent of any change of integu ments; and there is often a change of the integuments without transformation or any appearance of a new form: but a new form or change of appearance is always implied in metamorphosis or transformation. This new form is sometimes occasioned by a change of shape, consistency, and colour; as when the lobes of a seed are converted into seminal leaves. It is sometimes occasioned

by a change of proportions among the parts: the proportions of a fœtus, every one sees, are different from those of a full grown man; and the painter, merely by observing the proportions, represents a child, a dwarf, and a giant, on the same scale. It is sometimes occasioned by the addition of new organs; as when the emmet receives wings, and the plume of the seed is fed by new roots striking into the ground; or it is occasioned by a change of both the form and the organs, and their mode of operation, as happens remarkably in some insects: for, though all living bodies, plants and animals without exception, undergo partial or general transformations, yet these changes are chiefly observable among insects. Many insects appear to consist of two distinct animal bodies one within the other: the exterior, a creature of an ugly form, residing in the water or under the earth, breathing by gills or sometimes by trachea projecting from the tail, possessing a voracious and grovelling appetite, and having a system of sanguiferous vessels that circulates the blood towards the head. When all its parts decay and fall off, the creature inclosed succeeds in its stead: this often is an animal of a different form, generally lives in a different element, feeds on a different species of food, has different instruments of motion, different organs of sense, different organs of respiration, and differently situated; and, being endowed with the parts of generation, inclines to gratify the sexual propensity, and produces an embryo which becomes like the first, and from which afterwards in process of time a creature is evolved similar to itself.

If the embryo or egg be deposited on a leaf, the leaf frequently is observed to bend, to wrap it in folds intended for the purpose, and to protect it from injuries and danger. If deposited in the body of an animal or plant, they accommodate themselves to its wants and necessities, and furnish a tumour which serves it for a nidus, and besides, like an uterus, supplies it with nourishment; and if deposited in the body of an insect, the creature provides for the future destination of its young charge with all the tender care of a parent, and then dies.

These circumstances, added to the great variety of forms which insects assume, render it sometimes difficult to know who is the parent. We cannot, for instance, pronounce with certainty who is the true parent of the gordius, known by the name of the seta equina, or hair cel. A set of experiments, which we once began with a view to throw some light on the subject, were interrupted unfortunately by an accident, and we have not since had leisure to resume them. We learned only, from a number of observations, that certain black beetles about the end of the summer months have the strongest propensity to run into the water, where they soon die; and that one or two, and sometimes three or more, of those eels gradually drop from the beetle by the anus. Whether other insects provide for the gordius in this manner we have not yet been able to determine.

The transmutations of some animals are most observable in the uterus and egg and anatomy has often witnessed the change which happens at birth with respect to circulation, respiration, digestion, and the other functions.

If the reader wish to be much acquainted with the manners and transformations of insects, he will derive information and pleasure from consultin the plates and memoirs of Reaumur. If he w to know their intimate structure, the lab Swammerdam can introduce him to a r amusing species of anatomy. This last ?

before Reaumur defined and described the kinds of transmutations among insects and some other animals. He was shown similar transmutations in plants; and in plate 46 of his Book of Nature has compared the frog and the clove July-flower under their six different forms.

In all living bodies possessed of mind, the changes of form, as well as the change of habit and of age, are usually accompanied with new propensities, appetites, and passions. It may therefore be inferred, that we ought not to look for the cause of temper in either the brain or the nervous system; or to imagine, that the propensities, appetites, and passions, are properties of mind: they seem only affections happening to mind in consequence of stimuli and organic structure.

Microscopic observations having demonstrated, that all the forms of the plant and animal existed previously in the seed or embryo, transformation must be owing entirely to the evolution of the different parts by means of nutrition.

What nature intends by transformation, we pretend not to say; but by means of transformation different elements are peopled, the different seasons variously adorned, and animated nature wonderfully diversified without a multiplication of beings. For the various races of mankind, see the articles MAN and HOMO.

GENUS III. Decay and Death.

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Death is the cessation and total absence of the living principle in organized bodies. It is sometimes imitated by sleep and swoons; and a state of torpor in many instances can hardly be distinguished from it. Several mosses and a few animals, as the cars of blighted wheat, the seta equina, the wheel polype, and some snails as we learn from the Philosophical Transactions, may be safely preserved as dried preparations, not for months only but for years; and after irritability and sensation have been totally suspended, will return to life upon the proper application of moisture. A wheel lype was put by Fontana upon a bit of glass, and exposed during the whole sunimer to the neonday sun; another was exposed in a similar manner for a year and a half; and, after they were like a piece of hardened glue, were restored to the use of all their functions by a few drops of water. Where ever there is death, there must therefore be like wise a partial or general decomposition of one or more of the vital organs. This decomposition takes place naturally in some living bodies after a few hours, in some after a few days; the life of others is extended to weeks; some are vigorous for months or a season. Man has often seen more than fourscore; and the hardy oak survives the shock of two or three centuries. These observations conspire to show that there is a certain period of existence allotted by nature to every species of living bodies. In the individual this period is sometimes abridged, and may be sometimes extended by circumstances; but yet there is a bound which it cannot pass, when the vital organs must be decomposed, and the system return to moulder with the dust. The time of incubation and the time of gestation are pretty much defined in every species, because the circumstances of the individual in these cases are generally similar; but, after emerging from the foetal state, the individuals are partly entrusted to their own organs and the chances of life, which are much varied; and hence we account for the difference of their age.

Life in general seems to be proportioned to the space occupied by that series of functions which the species is evidently destined to perform: and

here sometimes the accommodating principle is singularly remarkable. As the period of decay is never seen to commence in the species till that of propagation be nearly elapsed, and as propagation in the lower tribes of plants and of animals is often the immediate harbinger of death; so many animals which have not propagated, indulged the propensity, nor become uneasy from the languor of desire, continue vigorous longer than ordinary, as as if it were waiting for an opportunity to multiply their kind. And in the vegetable kingdom, where no individual is ever the victim of desire or passion, annuals, if prevented from flowering and seeding in their proper season, will live double, and sometimes triple, the usual time, till these functions be somehow performed, and then die. But when all the organs are fully evolved and have discharged, or have continued for the usual time capable of discharging, those offices for which they were intended; dissolution commences, the assimilating organs begin gradually to lose their tone, and the re-absorbents carry off more from the different parts than what they receive in the way of nutrition: the irritable fibre then becomes rigid; the membranes and cartilages begin to ossify; the bones grow harder; the smaller vessels collapse and disappear; the parts no longer are obedient, as before, to the action of stimulants; and death en

sues.

Some, in order to account for this event, imagine that the body receives at first a certain portion of irritability, and continues to live till that be exhausted: but this theory explains nothing; and without pretending to a great deal of foresight, we will venture to predict, that for all the irritability which it has, it will not be distinguished for its longevity,

With regard to the periods by which the life, the functions, and diseases of living bodies are so frequently regulated, and which periods may sometimes be varied but not evaded, the most prudent

language that, perhaps, can be adopted in the present state of physiological science is this of the Divine, That the God who formed us hath numbered our days, determined our times, and prescribed the limits of our existence.

PHYSOCELE. (physocele, quoounan; from quae, wind, and x, a tumor.) Any species of hernia, whose contents are distended with wind.

PHYSOCEPHALUS. (physocephalus, que paλos; from purs, wind, and xipan, the head.) Emphysema of the head. See PNEUMATOSIS.

PHYSOMETRA. (physometra, quoqueria; from quow, to inflate, and up, the womb.) A windy swelling of the uterus. A genus of disease in the class cachexia, and order intumescentiæ, of Callen; characterized by a permanent elastic swelling of the hypogastrium, from flatulent distention of the womb.

PHYSSOPHORA. In zoology, a genus of the class vermes, order mollusca. Body gelatinous, pendent from an aerial vesicle, with gelatinous, sessile members at the sides, and numerous tentacles beneath. Three species, ovalorbicular or filiform. The orbicular, P. rosacea, an inch in diameter, and resembling The filiform, P. filiformis, a span long, a full-blown flower bending downward. not thicker than a thread, with an obtuse ovate head about the size of a grain of rice. They all inhabit the Mediterranean Sea, and are nearly allied to the medusæ,