[footnote] *Tacitus, in his speculations on the inhabitants of Britain ('Agricola', cap. ii.), distinguishes with much judgment between that which may be owing to the local climatic relations, and that which, in the immigrating races, may be owing to the unchangeable influence of a hereditary and transmitted type. "Britanniam qui mortales initio coluerunt, indigenae an advecti, ut inter barbaros, parum coompertum. Habitus corporis varii, alque ex eo argumenta; namque rutilae Caledoniam habitantium comae, magni artus Germanicam originem adseverant. Silu ram colorati vultus et torti plerumque crines, et posita contra Hispania, Iberos veteres trajecisse, easque cedes occupasse fidem faciunt: proximi Gallis, et similes sunt: seu durante originis vi; seu procurrentibus in diversa terris, positio coeli corporibus habitum dedit." Regarding the persistency of types of conformation in the hot and cold regions of the earth, and in the mountainous districts of the New Continent, see my 'Relation Historique', t. i., p. 498, 503, and t. ii., p. 572, 574.
In my opinion, however, more powerful reasons can be advanced in support of the theory of the unity of the human race, as, for instance, in the many intermediate gradations* in the color of the skin and in the form of the skull, which have been made known to us in recent times by the rapid progress of geographical knowledge — the analogies presented by the varieties in the species of many wild and domesticated animals — and the more correct observations collected regarding the limits of fecundity in hybrids.**
[footnote] On the American races generally, see the magnificent work of Samuel George Morton, entitled 'Crania Americana', 1839, p. 62, 86; and on the skulls brought by Pentland from the highlands ot titicaca, see the 'Dublin Journal of Medical and Chemical Science', vol. v., 1834, p. 475; also Alcide d'Orbigny, 'L'homme Americain considere sous ses rapports Physiol. et Mor.', 1839, p. 221; and the work by Prince Maximilian of Wied, which is well worthy of notice for the admirable ethnographical remarks in which it abounds, entitled 'Reise in das Innere von Nordamerika' (1839).
[footnote] ** Rudolph Wagner, 'Ueber Blendlinge und Bastarderzeugung', in his notes to the German translation of Prichard's 'Physical History of Mankind', vol. i., p. 138-150.
The greater number of the contrasts which were formerly supposed to exist, have disappeared before the laborious researches of Tiedemann on the brain of negroes and of Europeans, and the anatomical investigations p 353 of Vrolik and Weber on the form of the pelvis. On comparing the dark-colored African nations, on whose physical history the admirable work of Prichard has thrown so much light, with the races inhabiting the islands of the South-Indian and West-Australian archipelago, and with the Papuas and Alfourous (Haroforas, Endamenes), we see that a black skin, woolly hair, and a negro-like cast of countenance are not necessarily connected together.*
[footnote] *Prichard, op. cit., vol. ii., p. 324.
So long as only a small portion of the earth was known to the Western nations, partial views necessarily predominated, and tropical heat and a black skin consequently appeared inseparable. "The Ethiopians," said the ancient tragic poet Theodectes of Phaselis,* "are colored by the near sun-god in his course with a sooty luster, and their hair is dried and crisped with the heat of his rays."
[footnote] *Onesicritus, in Strabo, xv., p. 690, 695, Casaub. Welcker, 'Griechische Tragodien', abth. iii., s. 1078, conjectures that the verses of Theodectes, cited by Strabo, are taken from a list tragedy, which probably bore the title of "Memnon."
The campaigns of Alexander, which gave rise to so many new ideas regarding physical geography, likewise first excited a discussion on the problematical influence of climate on races. "Families of animals and plants," writes one of the greatest anatomists of the day, Johannes Muller, in his noble and comprehensive work, 'Physiologie des Menschen', "undergo, within certain limitations peculiar to the different races and species, various modifications in their distribution over the surface of the earth, propagating these variations as organic types of species.*
[footnote] *[In illustration of this, the conclusions of Professor Edward Forbes respecting the origin and diffusion of the British flora may be cited. See the 'Survey Memoir' already quoted, 'On the Connection between the Distribution of the existing Fauna and Flora of the British Islands, etc.', p. 64. "1. The flora and fauna, terrestrial and marine, of the British islands and seas, have originated, so far as that area is concerned, since the melocene epoch. 2. The assemblages of animals and plants compositing that fauna and flora did not appear in the area they now inhabit simultaneously, but at several distinct points in time. 3. Both the fauna and flora of the British islands and seas are composed partly of species which, either permanently or for a time, appeared in that area before the glacial epoch; partly of such as inhabited it during that epoch; and in great part of those which did not appear there until afterward, and whose appearance on the earth was coeval with the elevation of the bed of the glacial sea and the consequent climatal changes. 4. The greater part of the terrestrial animals and flowering plants now inhabiting the British islands are members of specific centers beyond their area, and have migrated to it over continuous land before, during, or after the glacial epoch. 5. The climatal conditions of the area under discussion, and north, east, and west of it, were severer during the glacial epoch, when a great part of the space now occupied by the British isles was under water, than they are now or were before; but there is good reason to believe that, so far from those conditions having continued severe, or having gradually diminished in severity southward of Britain, the cold region of the glacial epoch came directly into contact with a region of more southern and thermal character than that in which the most southern beds of glacial drift are now to be met with. 6. This state of things did not materially differ from that now existing, under corresponding latitudes, in the North American, Atlantic, and Arctic seas, and on their bounding shores. 7. The Alpine floras of Europe and Asia, so far as they are identical with the flora of the Arctic and sub-Arctic zones of the Old World, are fragments of a flora which was diffused from the north, either by means of transport not now in action on the temperate coasts of Europe, or over continuous land which no longer exists. The deep sea fauna is in like manner a fragment of the general glacial fauna. 8. The floras of the islands of the Atlantic region, between the Gulf-weed Bank and the Old World, are fragments of the Great Mediterranean flora, anciently diffused over a land consistuted out of the upheaval and never again subjerged bed of the (shallow) Meiocene Sea. This great flora, in the epoch anterior to, and probably, in part, during the glacial period, had a greater extension northward than it now presents. 9. The termination of the glacial epoch in Europe was marked by a recession of an Arctic fauna and flora northward, and of a fauna and flora of the Mediterranean type southward; and in the interspace thus produced there appeared on land the Germanic fauna and flora, and in the sea that fauna termed Celtic. 10. The causes which thus preceded the appearance of a new assemblage of organized beings were the destruction of many species of animals, and probably also of plants, either forms of extremely local distribution, or such as were not capable of enduring many changes of conditions — species, in short, with very limited capacity for horizontal or vertical diffusion. 11. All the changes before, during, and after the glacial epoch appear to have been gradual, and not sudden, so that no marked line of demarkation can be drawn between the creatures inhabiting the same element and the same locality during two proximate periods.">[ — Tr.