Crude, simple, and at first sight ludicrous as it may appear, it is nevertheless worthy of consideration that the negro is black, and, in the absence of moonlight or artificial illumination, can not at night be so readily seen as a white man; he may therefore on this account escape the sight, and consequently the bite, of the mosquito. The deep tint of his skin possibly constitutes a "protective coloring," such as in many other species affords a defense against natural enemies. Moreover, the habit, common with many negro races in their native heath, of daily anointing the body with grease, affords additional protection against mosquitoes, as do also, probably, the offensive odor and greasiness of his cutaneous secretions. In this connection the work of Dr. Balfour on "Sol-Lunar Influence" in malarial fevers, hitherto ignored, deserves reconsideration. The light of a full moon would render the negro more visible to his culicidal enemy.
When the negro is imported into this country, and subjected to the conditions of civilized life—which usually comprise, among the rest, his remaining during a part of the evening in rooms artificially illuminated, or sleeping with his black body portrayed in bold relief upon white bedclothing—the mosquital blood-suckers will then have little difficulty in finding their victim, notwithstanding his protective melanotic mantle.
The Conservative Function of Ague.—In my original paper, read before the Philosophical Society of Washington, on the 10th of February last (and of which, as I have said, the present production is an abstract), I suggested that the natural conservative design of the processes embodied in the term ague was to develop malarial melanosis—in fact, to change the skin from white to black, thus securing adaptation to (i. e., protection against) the environment of inoculating gnats, by clothing the individual with a cutaneous mantle of "protective coloring." The spleen I therefore regarded as the organ, one of whose offices is, as it were, to preside over and determine the cutaneous coloring of the individual—a function not hitherto ascribed to it; though its pigment-forming function, by destruction of blood-corpuscles in its substance, has been long known. The absolute transformation from white to black under the influence of malarial disease has been frequently observed (see a case by Dr. William II. Falls, in the "Cincinnati Lancet and Observer," November 18, 1882, pp. 479-488). Surgeon-General C. A. Gordon, in his account of the fever among the British troops in Cyprus ("London Medical Press and Circular," new series, vol. xxx, p. 303), in 1878, says: "The Forty-second Regiment suffered terribly at Cyprus; the men looked worse than they did on the Gold Coast—pale and sallow, or black (italics his), the pure malarial melanosis."
Be it noted, further, that the causes or conditions that lead to different tints of color in different races of men—since it is now known not to depend, as once supposed, upon heat of climate—is a complete