of Angola and the orang-outang of Borneo? Nor are there so many doubts about these, as about the domesticated animals, which are thus excluded.

The different breeds of dogs, for example, are referred by some to different species; and they are, indeed, sufficiently marked by distinctive permanent characters to warrant the opinion, if the constancy of such characters were a sufficient proof of difference in species. Others, again, refer them all to the shepherd's dog; and others include all the dogs, the wolf, fox, and jackal, in one species. The dog and bitch produce with the male and female wolf, and with the dog and bitch fox; and the offspring is prolific. Yet we cannot surely ascribe animals, which are marked in their wild state by such strong characters, of bodily formation, disposition, and habits, as the wolf, fox, and jackal, to one and the same species, without overturning all the fundamental principles of zoology, however freely they may intermix, and however perfect the reproductive power may be in their offspring,*

We may conclude, then, from a general review of the preceding facts, that nature has provided, by the insurmountable barriers of instinctive aversion, of sterility in the hybrid offspring, and in the allotment of species to different parts of the earth, against any corruption or change of species in wild animals. We must therefore admit, for all the species which we know at present, as sufficiently distinct and constant, a distinct origin and common date. On the other hand, the fruitful intermixture which art has accomplished, of some of these species, will not justify us in ascribing to them identity of race or origin, when we see them in the natural wild state distinguished by constant characters from the type of the neighbouring species, and always producing an offspring marked by these characters. Since neither the principle of breeding, nor the constancy * Pallas entertains the opinion that our sheep, dogs, and perhaps poultry, are factitious beings, not descended from any single wild original, but from a mixture of nearly allied primitive species, whose hybrid offsprings have possessed prolific powers. He observes that those domesticated animals, which either do not intermix with other species, or which produce with others unprolific progeny, are very little changed, however completely and anciently they may have been brought under the dominion of man; or at least are not so changed as to cause any difficulty respecting their origin. This is the case with the horse and ass in all climates; with the ox kind; with the pig; the camel and dromedary; and the rein-deer. He refers our sheep to intermixtures of the Siberian argali (ovis ammon), the mouflon of Corsica and Sardinia, that of Africa (ovis tragelaphus Cuv.), the wild goat of Persia (paseng, the bezoar animal, capra ægragrus), the bouquetin (capra ibex), and the wild goat of Caucasus (capra Caucasica). The dog he considers to have proceeded from the jackal wolf, and fox. Mémoire sur la variation des Animaux; Acta Acad. Petrop. 1780.

of particular characters, are sufficient in all cases to enable us to judge of species, and since these fail, particularly in the domestic kinds, where their aid is principally required, we must resort at last to the criterion recommended by BLU MENBACH, and draw our notions of species in zoology from analogy and probability. If we see two races of animals resembling each other in general, and differing only in certain respects, according with what we have observed in other instances, we refer them without hesitation to the same species, although the difference should be so considerable, as to affect the whole external appearance. On the contrary, if the difference should be of a kind which has never arisen, within our experience of the animal kingdom, as a variety, we must pronounce them to belong to distinct species, even although there should be, on the whole, a great general resemblance between the two. "I see," says this acute and judicious naturalist, a remarkable difference between the Asiatic and African elephants in the structure of the molar teeth. Whether these inhabitants of such distant regions will ever be brought to copulate together, and whether this formation be universal, is uncertain: but it exists in all the specimens I have seen or heard of, and I know no example of molar teeth changed in such a manner by degeneration, or the action of adventitious causes: therefore I conjecture, from analogy, that these elephants are not mere varieties, but truly different species. On the other hand, I hold the ferret (mustela furo) to be only a variety of the pole-cat (m. putorius), not so much because they produce together, but because it has red pupils; and the analogy of numerous other instances induces me to regard all the other mammalia, which are destitute of the colouring pigment of the eye, as varieties degenerated from their original stocks."*

This method is the only satisfactory one of investigating the varieties of the human species. The diversities of physical and moral endowment which characterize the various races of man, must be analogous in their nature, causes, and origin, to those which are observed in the rest of the animal creation; and must therefore be explained on the same principles.

There is no point of difference between the several races of mankind, which has not been found to arise, in at least an equal degree, among other animals, as a mere variety, from the usual causes of degeneration. Our instances are drawn chiefly from

* De Gen, hum. Var. nat. pp. 70, 71.

the domesticated kinds, which, by their association with man, lead an unnatural kind of life, are taken into new climates and situations, and exposed to various other circumstances, altogether different from their original destination. Hence they run into varieties of form, size, proportions, colour, disposition, faculties, which, when they are established as permanent breeds, would be considered by a person uninformed on these subjects to be originally different species. Wild animals, on the contrary, remaining constantly in the state for which they were originally framed, retain permanently their first character.

Man cannot be called, in the ordinary sense of the term, a domesticated animal; yet he is eminently domestic. Inhabiting every climate and soil, acted on by the greatest variety of external agencies, using every kind of food, and following every mode of life, he must be exposed still more than any animal to the causes of degeneration.

I proceed to consider the circumstances in which the several races of men differ from each other, to compare them to the corresponding differences of animals, and to show that the particular and general results of these inquiries lead us plainly to the conclusion, that the various races of human beings are only to be regarded as varieties of a single species. Whether this one species owes its origin to one pair, a male and a female, is a question which zoology does not possess the means of solving; a question which is of no more importance respecting our own species, than it would be in the case of the elephant, lion, or any other animal.

CHAPTER II.

On the Colour of the human Species.-Structure of the Parts in which the Colour resides.-Enumeration of the various Tints.-Colour and Denomination of the mixed Breeds.-Various Colours of Animals.-Production of Varieties. Spotted individuals-Other Properties of the Skin.

ALTHOUGH a general survey of organized bodies in both the animal and vegetable kingdom by no means leads us to regard colour as one of their most important distinctions, but, on the contrary, will soon convince us that it may undergo very signal changes without essential alterations of their nature; and although this remark holds equally good of the human subject; yet the different tints and shades of the skin, offering themselves so immediately to observation, and forcing themselves, in a manner on the attention of the most incurious, have always

been regarded by the generality of mankind as the most charac teristic attribute of the various races. These several hues form, indeed, very constant hereditary characters, clearly influenced by the colour of both parents in the mixed offspring of different varieties, and bearing a very close and nearly uniform relation to that of the hair and iris, as well as to the whole temperament of the individual.

The skin, in which the colour of animals resides, is a more or less dense membrane covering the surface, and generally proportioned in thickness to the volume of the body; serving the purpose of binding together and protecting the subjacent organs, of separating, under the form of sensible and insensible perspiration, a large quantity of excretory inatter, the residue of digestion and nutrition, and of establishing the relations between the living frame and surrounding objects. It is the sensitive limit of the body, placed at the extremity of the organs, incessantly exposed to external influences, and thus forming one great connexion between animal existence and that of surrounding substances.

Anatomical analysis resolves this apparently single envelop of our organs, commonly called skin, into two or more strata, technically termed the common integuments.

The most considerable and important of these, making up, indeed, the chief bulk of the skin, is the cutis vera, or true skin, dermis, corium, le corion Fr. ;-the part which, when prepared by the chemical process of tanning, constitutes leather. It is a compact and strong areolar tissue, composed of a dense fibrous substance, with numerous vacuities or intervals. The intertexture of the fibrous or cellular tissue is close and compact on its external surface, so as to resemble the smooth continuity of a membrane; more loose, with large areola on the opposite or adhering aspect; where the fibrous threads are lost in those of the subjacent cellular or adipous tissue. Immersion in water softens the skin by separating the fibres of its corion, and rendering their intervals more distinct: we then find that the areolæ are not confined to the external surface, but are prolonged into its substance, which is penetrated by them in its whole thickness. They serve for the passage of hairs, exhalants, and absorbents, as they come to the surface.

The areolar tissue of the cutis is permeated in every direction by countless myriads of arterial and venous ramifications, of which the ultimate capillary divisions occupy the external or

compact surface of the organ, and form a vascular network over the whole body, eluding our inquiries and defying calculation by the number and fineness of its tubes. In the glow of exercise or the flush of shame, in the excitement of fever, or the eruption of measles, scarlatina, &c. these cutaneous vessels are filled with blood; they may be injected with coloured fluids after death. Their ramifications are particularly numerous and subtle in those parts of the cutaneous organ which possess the most exquisite sensibility; and where the surface is found, on minute examination, to be covered by numerous fine processes called papillæ or villi.*

The absorbents of the skin seem nearly equal in number to its blood-vessels.

Numerous nerves enter it in all parts, and distribute their largest ramifications in the situations occupied by the papillæ.

The colour of the cutis is uniform, or very nearly so, in all the varieties of the human race, and depends entirely on the state of its capillary blood-vessels. According as they are full or empty, it may vary (as we see in the white races) from a more or less florid red, constituting what artists call flesh-colour, to the waxy paleness of fainting or exhaustion from hæmorrhage. Maceration in water makes its areolar tissue quite white; and injection with sise coloured by vermillion gives it a deeper or lighter shade of red, according to the force employed.

The cuticle or epidermis, the exterior layer of our common integuments, is the thin transparent or light grayish pellicle raised by a blister: in the natural state it adheres closely, almost inseparably, to the subjacent parts, and is accurately fitted to the cutis, having folds and lines corresponding to all the inequalities of that organ. It presents no traces of fibres, laminæ, or cells; it has no blood-vessels, absorbents, or nerves. Therefore, though perforated by the hairs, by the excretory tubes of cutaneous follicles, by the exhalant mouths of the capillaries, and possibly by absorbent orifices, it is incapable of sensation and all vital actions, extravascular, inorganic. It is a protecting sheath for the finely-organized and sensible skin, and serves the further purpose of preventing evaporation, by which that organ

The external vascular surface of the cutis, with its papillæ or villi, seems to be what Bichat has described as a separate stratum, under the name of corps reticulaire (Anat. générale). I have never seen the distinction. My object, here, is not however to describe the skin fully, but merely to consider it as the seat of colour. They who wish for further information on the structure of the integuments may consult Dr. Rees' Cyclopædia, art. Integuments; and Dr. Gordon's System of Human Anatomy, book ii. chap. 4.