said, of an atrophy, while the usurping Newche stepped into his shoes, and was obeyed by his family with a devotion which they had scarcely been willing to exhibit toward his own authority. The worthy burgher slept quietly in the Dutch church-yard in Garden-street, (at least till the great fire,) while his house was transmuted in such sort that if he could have revisited 'the glimpses of the moon,' he would never have known it to be the same. The nearest approach to such a return of our friend has been the appearance of a form like his on the surface of a polished mirror, once owned by a beneficent enchanter, who allowed the public the benefit of its pleasant revelations. Since this hand of power abandoned the magic glass it is occasionally taken up by a passing stranger; but it is only to make us recollect that the glory is departed.'

If Diedrich could walk Broadway just now, he would probably imagine that he had taken but a moderate nap; for the whale-boned waists, the pointed bodices, the voluminous skirt and its accompaniments, the close sleeve and the long-eared bonnet, which now adorn his fair descendants, seem almost like a resuscitation of the fashions which capricious Newche then sought to drive out from the land. But he would find the reign of the phantom as despotic as ever; so we recommend to him to lie still. Requiescat!

THOUGHTS ON ANIMAL НЕАТ.

BY

A NEW CONTRIBUTOR.

VARIOUS have been the theories advanced by chemists and physiologists to account for the phenomenon in the animal economy known as animal heat. By some, among whom Dr. Black stands foremost, it is supposed to be due entirely to the chemical action which takes place during respiration, by which oxygen gas is taken from the atmosphere and carbonic acid gas evolved. Were the fact established that the carbonic acid gas exhaled was due to the action of oxygen on the carbon which is supposed to be contained in the blood, the caloric which would necessarily be given out during the chemical action would undoubtedly have some effect in the production of animal heat. But even in that case, the caloric thus produced and transmitted by the veins to every part of the body would hardly account for an amount of heat so great as to keep up in the animal system a uniform temperature many degrees higher than the common temperature of the surrounding atmosphere.

But in addition to this, the whole theory of the action of oxygen gas on carbon in the production of the carbonic acid gas, has been disputed; and it has been shown by Dr. Edwards that the phenomenon can be accounted for by the absorption of oxygen and the throwing off carbonic acid gas directly from the lungs, in consequence of its previous existence in the blood. That the lungs will absorb one gas and give off another which must have existed previously in the blood, was proved by Dr. Edwards in a number of experiments. An animal was placed in an atmosphere composed entirely of oxygen and hydrogen, and at the close of the experiment a quantity of hydrogen had been absorbed and a portion of nitrogen greater than the bulk of the animal was contained in the residual air. This then being the case, we may arrive nearer the true cause of the whole of the large quantity of caloric contained in the animal system, by the supposition that the carbonic acid gas is formed by chemical action in the blood during its passage through the veins. This action would of course produce a large quantity of caloric which would have immediate access to the flesh and the surface of the skin. And does not the supposition deserve notice from physiologists, that the oxygen taken into the lungs during the act of respiration is the principal cause of the color of the blood, a subject which has been so long and unsatisfactorily investigated by chemists? The coloring matter is now generally believed to be owing to the existence of oxide of iron in the globular particles; the difficulty is to account for its existence and action.

Now it is known by experiment that a portion of iron does exist in the venous globules; and may not the absorption of oxygen during respiration, by its action upon this iron, produce the peroxide of

iron, which is necessary to its red color? And this will account for the fact that the blood does not receive its floridity of color until after its passage through the lungs, exhibiting in its previous state a dark purple color, which is perhaps due to the formation of carbonic acid and the presence of iron. However this may be, it does not affect the truth of our hypothesis with respect to its transition from one color to the other. The chemical action which is going on in the production of the carbonic acid gas would give off caloric enough, in connection with the effect produced by the nervous system, to account for the high temperature of animal bodies, known as animal heat.

To this it may be objected that this theory does not account for the fact that an increase in the length and frequency of the respiratory breathings, and consequent increase in the quantity of carbonic acid gas evolved, caused by violent bodily exercise, as running, labor, etc., gives rise to a corresponding increase of temperature; a fact which is easily explained by, and is indeed a natural consequence of, the truth of the opposite theory, that the heat is generated by the formation of carbonic acid gas by means of the action of oxygen on the carbon supposed to exist in the blood. To this I would answer by begging of my antagonist to inform me how it is that by bodily exercise, all the functions of the body are preserved in a state of activity, the free circulation of the blood kept up, and the general tone of the system rendered healthy? It is vain to urge in opposition to a theory, its non-capability to account satisfactorily for phenomena which will require a more thorough knowledge of the nature of chemical action, and indeed of the very elements of the science to investigate and explain. If such objections are to be considered valid there is no hypothesis, however ingenious and applicable it may be, and however generally received by scientific men, but would be overthrown by those who look rather to the arguments which can be urged in opposition to a scheme than to the gradual advancement of science to certainty and perfection.

Without affirming positively then that no explanation can be given in accordance with this theory, of the phenomena alluded to, I will simply say that it by no means is necessary to its reception as true. To the other scheme, bearing as it does such evidences of its falsity on its very face, the mere fact of its accounting for the phenomenon in question is of no avail. The former theory then, supported as it is by such men as Dr. Edwards, La Grange, and others, and backed by their numerous and conclusive experiments, grounded on and chiming in also with the general opinion of the coloring of the blood being due to the presence of peroxide of iron, so ably confirmed by the experiments of that excellent chemist, Dr. Engelhart, we think should be regarded as true. In connection with which, we would recommend to chemists the consideration of the theory advanced by us with respect to the coloring of the blood, which is entirely consistent with, and is indeed confirmed by, the truth of the theory which we have advocated, in regard to the production of animal heat.

Columbia, (S. C)

GILES.