under proper treatment, and favorable circumstances, it frequently happens, that these chemical laws of affinity become again suspended, and the natural healthy laws of the animal again restored; the fluids regain their pristine sweetness, the sensibility its proper standard, and a complete restoration of animal strength and power is the result. There must, therefore, unquestionably exist in animals a power of generating some principle by which the chemical laws of matter are subverted, and this principle is electric fluid, by the agency of which I have assumed sensibility to be effected. And this fluid (the electric) is elaborated from the received food, by the action of that series of organs which have hitherto been regarded as labouring only for the re-building of a continually mouldering structure.

In support of this opinion, I may observe, that I have never seen a single instance of general putrescency where the assimilative functions have been tolerably natural, except where the food has been of defective quality. And a return of appetite has been the period from which I have always prognosticated with certainty, a cessation of the putrefactive process, and a return to animal combinations, in

those instances where putrescency has greatly prevailed. If digestion, and all those processes embraced in the notion of the assimilative functions, were not for the purpose I have assumed, but merely for the rebuilding of a continually decaying body, the relative supply of food required, should have accorded with the relative size of the animal: but this is not the case, for the smaller animals consume much greater relative quantities of food than the larger. The voracity of children is proverbial; the difference in the quantity of food consumed by small and large men is imperceptible; the larger animals are temperate; while the smaller are by natural necessity voracious. Thesé differences in the required relative supplies of food, may not perhaps be apparent, unless the 'attention be carried to, and observation made upon, the very large and small animals. The very small animals are then seen to consume daily a quantity of food equal, and oftentimes surpassing, their own bulk; while the larger ones require several weeks to consume a quantity equal to their bulk. In proof, compare the relative quantities of food consumed by the elephant, camel, &c., with those consumed by wasps, beetles, flies, &c. Or taking two animals who feed upon the same food, observe the com

parative quantities consumed by the rabbit and the horse; the former soon consumes a quantity equal to its own bulk, but a quantity equal to the bulk of the horse would not be consumed by him in several weeks. An animal that is not kept in relation with the laws of the material world, by the combined action of its arterial and nervous system, may remain months without food, without undergoing a chemical decomposition, as may be observed in the dormouse, and other hybernating animals; and, for a much longer period, as has been known of flies, which have remained torpid for years. On the contrary, animals who are excited to a preternatural vigilance, require unusual quantities of food. The required supply of food then does not correspond with the size of the animal, but is increased in the smaller, and decreased in the larger sensibility has also been shown to be necessarily increased in the smaller, and decreased in the larger, animals: from these circumstances, and the facts of torpid animals living without food, while those who are preternaturally excited, require unusual quantities, I am led to conclude, that the required quantity of food corresponds very much (although as I shall hereafter show, not altogether) with the required degree of sensibility, and hence, that

the ultimate use of the assimilative organs and food-taking is, the supply of electric fluid, upon the agency of which I have assumed sensibility to be dependent.

This view of the ultimate uses of the assimilative organs will be further borne out in a more extended consideration of animal existence, for which we shall hereafter be better prepared, by an advanced examination of the circumstances connected with life in the next part of our inquiry, as well as by a consideration of the nature of some diseases to be spoken of in a later part of this paper.

CHAPTER V.

i.

The Lungs-bring the blood into contact with the air -supposed object of this questioned and disproved -Animal heat-no fixed degree essential to lifethe degree of heat an adventitious circumstance— source of heat and use of the Lungs-argument in support-on media influencing the degree of heatFishes Amphibia-Insects-Conclusion.

SITUATED in, and nearly filling, the chest, (in man) are some fleshy sponge-like bodies, very permeable to air and exceedingly vascular, called Lungs. The evident design of these bodies, apparent both from their structure and function, is to bring into contact with the surrounding medium a large surface of the circulated blood. Of the exact chemical combinations and results thus effected, there is but little agreement among experimenters, scarcely any two inquirers having come to the same conclusion. These organs, however, are of such considerable importance in the animal economy, and, unfortunately in this country, so frequently the seat