attacks in consequence of fits of anger. She was the mother of two children, the second of which she had weaned, after nursing it a year, about five months previous to entering the hospital, and had never menstruated since her last confinement. Her skin then presented a general blackish tint, like that of a Mulatto, which she affirmed did not appear until she weaned her last child, when it came on almost at once, and at first increased gradually, and then very slightly decreased. It was nearly universal over the whole surface, except below the knees, where it suddenly stopped, the lower extremities being much less brown than other parts. It was more marked about the external surfaces of the joints, and the lips and the lower eyelids were of a very dark color. The conjunctivæ were but slightly changed in color. She was suffering under amenorrhoea, with derangement of the digestive organs.

Under the use of sulphur baths, the first patient became paler; after which, chlorine baths were used, which sensibly made the skin yellowish, but without restoring its natural color. In the second case, both simple and sulphur baths were used, without any appreciable effect upon the morbid color of the skin.

In our own case, no remedial means were used with reference to the alteration of the color. The symptoms with which it was accompanied, though not accounted for by the autopsy, were not the less instructive; while the interest of the case is enhanced by the fact that the nature of the change was verified by microscopical examination of a portion of the skin after death, which was not done in any of the recorded cases with which we have met.

Observations on the Causes of the Diversity of Complexion in the Dif ferent Nations of the Earth. By WM. G. MEACHEM, M. D.

Among the many interesting, yet perplexing queries that have engaged the attention of naturalists, but few have enlisted their feelings more warmly, or encountered more abundant material for contradictory theories than the following one: To what is the great diversity of complexion among the nations of the earth attributable?

Some authors have been disposed to believe, or, at least, to express it as their belief, that as many distinct species of men were originally created as there now exist different colors among them. But it is not befit

ing us, of this Christian age, with the Mosaic history of the creation in legible characters open before us, to give this relic of heathenism or offspring of infidelity (call it as you will), more than a bare mention. Others again, I believe, entertain the opinion that Shem, Ham, and Japheth, the primogenitors respectively of the Asiatics, Africans, and Europeans, were themselves characterized by distinct grades of color, which have been transmitted through successive generations down to the present time. This view, however, it is manifest, involves the necessity of a miraculous intervention in the outset, or, to say the least, an occurrence without a known parallel in nature-the procreation by the same parents of three distinct species of human beings, entirely dissimilar in form, color, &c. Indeed, I do not deny that with the Omnipotent this was possible, that He could have caused this wonderful phenomenon to appear as easily as he had previously fashioned man from the dust of the earth, and breathed into him the breath of life; but since we find no record to this effect upon the sacred pages, and since we are possessed of ample materials from the laboratory of reason and philosophical knowledge wherewith to effect the solution of this scientific inquiry, we are bound by all the requirements of logic and common sense to seek no farther; nor are we quixotically to venture into the mazes of fancy and miraculous interposition, or, above all, to build our hypotheses upon the ideal ruins of sacred Scripture.

But the most ancient, most generally received, as well as most philosophical cause hitherto assigned, is the influence of climate, and more particularly that component part of it denominated temperature. As a rule, it is observable that, making the temperate regions the point de depart, the complexion of mankind darkens in a ratio with the increase of their proximity to the torrid zone; the blackest hue, that of the genuine Negro, being indigenous solely within the tropics, where, of necessity, the solar heat is the most continuously and intensely experienced. Thus, among the natives of the middle division of the north-temperate zone, embracing the greater portion of the United States, Great Britain, Germany, Prussia, Georgia, Circassia, &c., are found by far the fairest tints. In the southern portion, comprising a share of Mexico, southern United States, Spain, Italy, Turkey, the northern portion of Hindostan, &c., the prevailing hues are olive and brown. In the northern section of the intertropical belt, the color is still more deeply marked, exhibiting the lighter shades of black; but for the equatorial district is reserved the honor of giving birth to the ebon tinge, the "jet-black," as it is termed, of the unadulterated specimen of the Negro race.

In our advance from the poles to the temperate zones, we do not find the previous rule applicable, but rather the reverse-the complexion, instead of increasing, sensibly diminishes in darkness. This, however, does not in the least militate against the principle just advanced, but rather corroborates it-both extremes of climate producing the same change, but one much more considerably than the other. A very natural inference from a careful comparison of these facts, is, that the diversities of color, so numerous among men, are in great measure, if not exclusively, due to varieties in degree of temperature, the extreme of heat inducing an incomparably denser dye than the opposite extreme of cold.

Although many more circumstances might easily be put in the scale, that would materially augment the already exclusive preponderance of evidence favorable to the doctrine laid down in the preceding paragraph, still, deeming those adduced above sufficient for our present purpose, which is not so much an attempt to prove this doctrine by referring to facts known to every one and deducing therefrom principles, as an endeavor, presupposing the doctrine already established beyond question, to explain the phenomenon upon accredited physiological and chemical principles-believing, I repeat, that sufficient for my present object has already been said upon this particular, I desist from this part of the inquiry, to take up the more immediate subject of investigation, the modus operandi of the sun's rays in instituting these changes of color.

Should I fortunately succeed in presenting a rational, scientific, unexceptional theory, demonstrative of the minute changes which the sun's light, in accordance with the view just presented, effects in the human system to occasion these remarkable shades of complexion, this success of itself will be a weighty argument in the confirmation of that view, if not of direct, still of positive, collateral value.

As an initial step in this investigation, the location of complexion in the human being must be ascertained. This, as settled by the standard physiological authorities of the age, is the epidermis, as now considered, i. e., including what was originally regarded a distinct tissue, the layer immediately external to the outer layer of the cutis vera, and denominated rete mucosum. The color itself is due to the distribution throughout this epidermis of cells filled with a fluid whose hue is that of the particular individual complexion, and designated as pigment cells. These pigment cells seem to have their origin, equally with the proper cells of the epidermis, from the surface of the corium, and doubtless, also like them, are developed from reproductive granules distributed throughout

the true skin. These cells gradually approach the surface of the body, becoming flattened and condensed as they advance, until at last they acquire the character of horny scales, and, in conjunction with the other epidermic cells, fulfill the duty of protection to the more delicate structure immediately beneath. The characteristic hue of these cells is lo cated, not in the cell-wall, which in all probability has a composition identical with that of cells in general, fibrine; but in the contents of the cells, which consist of innumerable flat, rounded, or oval granules, having the diminutive diameter of one-twenty thousandth of an inch. The chemical composition of this pigment, that is, the contents of the cells, as it occurs in the white races, has not been, so far as I am informed, accurately determined if at all investigated; but it has been shown that carbon enters largely into that of the black pigment of the dark-colored races, every 100 parts containing 58 of this element.

Let it be our endeavor now to connect these two ascertained facts :1st. That the increase in the darkness of the human complexion is commensurate with the increase of proximity to the equatorial regions; and 2dly. That the element carbon, constitutes more than one-half of the black pigment of the negro. To connect these two facts, I repeat, with that telegraphic wire, the visible relation of cause and effect; for that they bear to each other that relation, I have little doubt.

The probability is, that both the light and the heat of the sun's rays are concerned in the causation of this wonderful phenomenon; but if I were to ascribe any excess of influence to either, that one would be the latter. Now, what chemical relation can we trace out between the application of light and heat and the production of carbon? Physiology teaches that the pigment cell-walls are endowed with a secerning power, by which they take from the blood circulating in that portion of the corium upon which they are developed, and store up in their own cavities, the materials peculiarly suited to their function. Whether these materials, after being conveyed into the cavities of the cells, there remain unchanged from their state in the circulating sanguineous fluid, or whether they there undergo chemical and physical transformations through the agency of the cell-wall, or of external influences, such as light, heat, &c., is a query, I believe hitherto not satisfactorily determined, but one well worthy of the attentive consideration of the physiologist. But, reasoning from analogy, as from the physiology of the hepatic and renal secreting processes, I am strongly tempted to believe that the pigment cell-wall possesses no other power than that of elimi

nating from the blood the various substances required to fill the cell-cavity, and therefore does not induce in those constituents any change; but I am not so certain that external stimuli have no chemical or physical influence upon them. Indeed, I feel no inconsiderable confidence in venturing the assertion that they have a decided influence upon them. The blood of the capillaries, which is at all times passing from the arterial to the venous state, must furnish the raw material; but I firmly believe that in the workshop of the pigment-cells the machinery of the chemical and vital stimuli, light, heat, &c., manufacture out of this raw material that peculiar fabric, the pigment.

And here allow me to suggest a theory: it is this,-That the augmented light and heat of intertropical countries stimulate the pigment cells to a much greater secreting power than they possess in colder latitudes, and that much larger quantities of carbonic acid are therefore conveyed from the capillaries into the cells; for there can be no question that the carbonic acid which is formed in the deoxygenation of the blood, in the intermediate system of blood vessels, is the source of all the carbon which constitutes so considerable a proportion of the pigmentary substance. It is rather unfortunate that we are as yet ignorant of the constitution of the residue of the black pigment; but what we already know is, I think, sufficient to explain the phenomenon of color; for it is well known that all forms of carbon, with but one exception, the diamond, are possessed of more or less blackness of hue, and some of an intensely sable tinge. I will refer to charcoal, bituminous and anthracite coal, plumbago, lampblack, coke, &c. as examples. So large a share of carbon as fifty-eight and one half per cent. is assuredly sufficient to darken well nigh any compound into which it may enter. Before concluding, however, that carbon gives the characteristic color, I should have premised that the carbonic acid which enters the cell-cavity must undergo resolution into its simple elements through the combined action of the light and heat of the sun.

Indeed, the disposition of the sun to increase the secretion of carbon, is manifested in other instances than the one under consideration. The hepatic secretion, which contains no inconsiderable amount of carbon, is a notable instance in point; for it is a well-known physiological fact that the bile is much more copiously excreted in hot climates and seasons than in those whose temperature is lower in the scale.

Again, certain processes going on within the body which call for increased action, and consequently augmented rapidity and fullness of cir