Very little appears to be known, at least scarcely any intimation is given in the work before us, of the proximate or final cause of these changes. Great as they are, certainly, as far as we can judge, no nisus formativus can account for the enormous horns of the Spanish sheep; nor, looking to the final cause; does there appear any reason why domestic animals should need such overgrown instruments of defence. When, however, we come to the more important anatomical modifications, such as the length and shape of the legs, the bones of the pelvis or of the jaw, the object is more apparent. A greyhound, with the muzzle of a bull-dog, would be an obvious natural inconsistency.
We now pass to the physical distinctions of the different races of men. Here we may observe that a much greater importance is to be attached to comparatively slight variations. Considering the surprising external differences that exist in domesticated animals of the same species, the wonder rather is, that the different races of men differ physically so little as they do, than that they differ so much. Here we will take first, the least important shades of difference—the texture of the skin, hair, and complexion; and then pass on to the more prominent diversities of the bony fabric, cranium, &c.
“The texture of the body, in which all these varieties have their seat, is the extracorial or exodermal structure, constituting, if I may so speak, the outer coating of the body, external to the true skin, which corresponds to the cuticular and corneous excrescences of animals—a structure which includes horns, hoofs, hair, feathers, and all similar appendages in different orders of animals. This structure displays infinite diversities in colour, constitution, and organization, and is the most variable tissue on the whole body. Many different opinions have, however, been lately maintained, and much research has been made, as to the nature and texture of the parts on which the variety of colour depends.”
The ancient anatomists, it appears, recognised only two parts of the skin—the true skin, and the outer cuticle or epidermis. Malpighi discovered a third layer interposed between these, consisting of a sort of network, thence called rete mucosum, and believed to be the seat of colour in the negro. Albinus showed this to be a continuous layer, and not a network. Cruikshank discovered four layers—three membranes, and the fourth a layer of colour. Flourens, at a more recent period, made the number of intermediate layers five, four of which he showed to the French Academy; one of these, a mucous membrane underlying the pigment, is, according to this anatomist, a distinct organized body, existing only in men of dark colour, and entirely wanting in the white races, or else (which appears the more probable conjecture) maceration, and the ordinary process of examination, fail to detect it in the skin of white men. Lastly, the microscopical researches of Henle, Purkinje, and Schwann, go to prove that the outer integument does not consist of separate membranes, but is of a cellular structure, and that of these cells or “cytoblasts,” there are three distinct kinds. We will not further analyse the different opinions as to the texture of the skin and position of the colouring material; it certainly throws no inconsiderable degree of doubt over certain classes of scientific investigation, to find each subsequent research entirely altering, and in some cases overturning, the previously received views.
To the different characters of human complexion, Dr Prichard gives three distinctive terms—the melanous or brunette; the xanthous or blonde; and the leucous or albino; the melanous predominating in the southern countries, the xanthous in the northern. It is observable here, that although the natural divisions of territory with respect to complexion, (supposing climate to have the principal modifying effect upon complexion,) would be the equatorial and polar regions, or the zones of the earth which differ in latitude, yet, with some few exceptions, it is only on the northern side of the equator that the xanthous complexion prevails—the inhabitants of Australia and the South Sea Islands being very generally melanous. The distribution of land and water cannot well be conceived to have any influence upon climate which would account for such diversity; it is probably, therefore, a result of long-continued civilization, the covering the body with clothes, and being for the most part sheltered from the direct rays of the sun. The leucous complexion is an abnormal variety, and occurs occasionally in all countries. It proceeds from the absence of the dark colouring matter, or pigment; there appears in this case, however, no difference of anatomical structure, the pigment being sometimes subsequently developed in persons who have been born albinoes. The change from the xanthous to the melanous complexion, is a circumstance of constant occurrence; there are few children born, whose complexion does not darken as they grow up, in many cases undergoing a total change: the passage from dark to fair is rare, but it constantly occurs that xanthous, or even leucous children, are born of melanous parents. There is nothing, therefore, in the diversities of complexion which indicates specific diversity in different human races. Of the conformation of the bony fabric in the human race, the formation of the skull is the part of the greatest importance; we shall only therefore briefly notice, as to the other parts of the skeleton, that between the most uncultivated races of men, and those tribes of apes which most nearly approach man, there is a wide difference—the arms of the orang-outang reach to the ankle, and those of the chimpanzee below the knee; the pelvis, or central bony fabric, differ much from those of the human race.
With regard to the skull, the value of the distinctions in its form and structure depends upon their connexion with the size and organization of the brain—involving the question, whether this has any, and what, influence upon the powers and habits of the creature. Dr Prichard, as we have already stated, blinks the question of phrenology; though he makes some inferences which prove him to have a general belief in the connexion between mental power and physical formation; nay, further, in the appropriation of different portions of the brain to different faculties.
Few will, we believe, in the present day be disposed entirely to deny that, ceteris paribus, the external formation of the skull, or rather the shape of the brain as shown by the formation of the skull, is a general index of the mental power of the individual to whom it belongs. Look over a collection of busts, or portraits, of eminent men, and, with scarcely an exception, they will be found to have high and capacious foreheads; while uncivilized races, and born idiots, are lamentably deficient in this respect. The difficulties of phrenology exist in its details, which by many have been carried out into degrees of subdivision certainly not warranted either by the anatomical structure of the brain, or by any empirical data as to the form of different crania, and the biography of the individuals to whom they have belonged. Where, in the existing state of our knowledge, the proper mean may be, it is perhaps difficult to say; but it would have been well, we think, had Dr Prichard given us a little more explicitly his opinions as to what extent phrenology (we use the word in its broadest sense) may be fairly relied on. As far as we can gather from the scattered passages in his book, he seems to take a rational view of it; but a little less caution would certainly have been more instructive to his readers, not only on the subject of phrenology, but on many of the connexions between physical structure and the habits to which such structure is adapted. This is a hiatus in Dr Prichard’s work, the filling up of which would add much interesting matter, and serve to weave together acts which at present are disjointed and isolated; giving the book a dry character, and preventing its arresting the attention of the reader. Throughout a larger portion of the work also, we have, in every third page or so, a minute description of the complexion, hair, &c., of different people; which, however valuable as matter of record, becomes tiresome and uninteresting as a continuous narrative, and would be much better thrown into a tabular form, as matter of reference only, if incapable of being so linked as to present a plausible theory.
The following passage is the most explicit we can find on the subject of the connexion between the physique and morale, and, at the same time, will serve to introduce the three varieties of skull which the author deems principally worth notice:—
“If any method of subdividing the human family into groups, is likely to be of any particular advantage in elucidating the natural history of the species, it must be one founded on some relation between the physical characteristics of different tribes and the leading circumstances of their external condition.
“We shall clearly perceive, in tracing the following outline of ethnography, that the varieties of colour refer themselves, in part, to climates, elevations of land, proximity to the sea-coast, or distance from it. It can hardly be doubted that these conditions have likewise an effect on the configuration of the human body. But there is, perhaps, some truth in the remark, though frequently made on little better foundation than conjecture, that the prevailing form or configuration of the body is more liable to be influenced by the habits of different races, and their manner of living, than by the simple agencies of climate. It would be an interesting discovery, could it be shown that there is any apparent connexion between the display of particular forms, or the leading physical characters of human races, and their habits of existence. If I may venture to point out any such relation, it would be by remarking, in a very general manner, and without pretending to make the observation as one which holds without many exceptions, that there are in mankind three principal varieties in the form of the head and other physical characters, which are most prevalent respectively in the savage or hunting tribes, in the nomadic or wandering pastoral races, and in the civilized and intellectually cultivated divisions of the human family. Among the rudest tribes of men, hunters and savage inhabitants of forests, dependent for their supply of food on the accidental produce of the soil or on the chase, among whom are the most degraded of the African nations and the Australian savages, a form of the head is prevalent which is most aptly distinguished by the term prognathous, indicating a prolongation or extension forward of the jaws; and with this characteristic other traits are connected which will be described in the following pages. A second shape of the head, very different from the last mentioned, belongs principally to the nomadic races, who wander with their herds and flocks over vast plains, and to the tribes who creep along the shores of the Icy Sea, and live partly by fishing, and in part on the flesh of their reindeers. These nations have broad and lozenge-formed faces, and what I have termed pyramidal skulls.