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The phænomena of electricity and of life correspond. Electricity may be attached to, or inhere, in a wire; it
may be suddenly dissipated, or have its powers annulled, or it may be removed by degrees or in portions, and the wire may remain less and less strongly electrified, in proportion as it is abstracted. So life inheres in vegetables and animals; it may sometimes be suddenly dissipated, or have its powers abolished, though in general it is lost by degrees, without any apparent change taking place in the structure; and in either case putrefaction begins when life terminates.
The motions of electricity are characterized by their celerity and force ; so are the motions of irritability. The motions of electricity are vibratory ; so likewise are those of irritability. When by long continued exertion the power of
muscles is fatigued, or when it is feeble, their vibratory or tremulous motions are manifest to common observation, but the same kind of motion may be perceived at all times by attention, as has been shewn by Doctor Woolaston in the Croonian Lecture for the year 1810.
1810. It is then I think manifest, that Mr. Hunter's conjectures are the most probable of any that have been offered as to the cause of irritability.
My allotted time does not permit me at present to consider the other vital functions ; yet I relinquish the subject with reluctance, because I have been speaking only on that point in which it seems most difficult to persuade the incredulous, of the probability and rationality of Mr. Hunter's Theory.
of the other vital functions, I think it will appear that it is impossible to account for the phænomena in any other manner than that which Mr. Hunter has · suggested.
In ascending the difficult and lofty ladder of knowledge, men of great talent and industry seem to have affixed to it certain resting places, on which, reposing for a time from their labours, they could tranquilly assemble their followers, and contemplate more extensive views of nature, and of nature's laws, than had before been taken. If after having stood by the side of the great teacher Newton, and learned from him the properties of common and inanimate matter, we afterwards attend to Mr. Hunter, our great instructor in the functions of living beings, he' points out to us how matter, starting from the
general mass, springs up into life in vegetation. We see vegetables as it were self formed and producing their
their own species. We observe them also exerting most of the powers which animals possess. That they have irritability is evident from the current of their
and their secretions ; nay, in some we observe those vivacious motions which seem chiefly to belong to animal life, as is evident in the Mimosæ, the Dionæa Muscipula, and Heydysarum gyrans.
We see them like animals having alternate seasons of action and repose; and though in general vegetables like animals are in action during the day and rest in the night, yet also some vegetables like some animals, rest in the day and are in action during the common season of
We see animals scarcely differing from vegetables in their functions, like them
doomed to a stationary existence, with even less appearance of organization than we usually discover in vegetables, and of a structure so simple as to admit of propagation like vegetables by cuttings. . Yet in all the diversity of living beings we recognize certain processes peculiar and essential to life; as the.
of converting other kinds of matter into that appropriate to the individual it is to form and support; the power of distributing the nutriment, thus converted, to every part for its formation and supply; the ventilation, as I may call it, of the nutritive fluids; the power
of preparing various dissimilar substances from the nutritive fluids; and the propagation of the species. As what is deemed the complexity of animal life increases, we find distinct organs allotted for each of these functions ; thus we have organs of digestion, circulation, respiration,