facts have been collected with respect to the transmission of the most trifling, as well as of the most important characters in man, than in any of the lower animals; though the facts are copious enough with respect to the latter. So in regard to mental qualities, their transmission is manifest in our dogs, horses, and other domestic animals. Besides special tastes and habits, general intelligence, courage, bad and good temper, &c., are certainly transmitted. With man we see similar facts in almost every family; and we now know, through the admirable labours of Mr. Galton," that genius which implies a wonderfully complex combination of high faculties, tends to be inherited; and, on the other hand, it is too certain that insanity and deteriorated mental powers likewise run in families. With respect to the causes of variability, we are in all cases very ignorant; but we can see that in man as in the lower animals, they stand in some relation to the conditions to which each species has been exposed, during several generations. Domesticated animals vary more than those in a state of nature; and this is apparently due to the diversified and changing nature of the conditions to which they have been subjected. In this respect the different races of man resemble domesticated animals, and so do the individuals of the same race, when inhabiting a very wide area, like that of America. We see the influence of diversified conditions in the more civilised nations; for the members belonging to different grades of rank, and following different occupations, present a greater range of character than do the members of barbarous nations. But the uniformity of savages has often been exaggerated, and in some cases can hardly be said to exist." It is, nevertheless, an error to speak of man, even if we look only to the conditions to which he has been exposed, as “far more domesticated "12 than any other animal. Some savage races, such as the Australians, are not exposed to more diversified conditions than are many species which have a wide range. In another and much more important respect, man differs widely from any strictly domesticated animal; for his breeding has never long been controlled, either by methodical or unconscious selection. No race or body of men has been so 10 Hereditary Genius: an In- man had an oval visage with fine quiry into its Laws and Conse- features, and another was quite quences,' 1869. "Mongolian in breadth and promi"nence of cheek, spread of nostrils, "and obliquity of eyes." 12 Blumenbach, 6 Treatises on Anthropolog.' Eng. translat., 1865, 11 Mr. Bates remarks (The Naturalist on the Amazons,' 1863, vol. ii. p. 159), with respect to the Indians of the same South American tribe, 66 no two of them were at all similar "in the shape of the head; one แ 66 p. 205. completely subjugated by other men, as that certain individuals should be preserved, and thus unconsciously selected, from somehow excelling in utility to their masters. Nor have certain male and female individuals been intentionally picked out and matched, except in the well-known case of the Prussian grenadiers; and in this case man obeyed, as might have been expected, the law of methodical selection; for it is asserted that many tall men were reared in the villages inhabited by the grenadiers and their tall wives. In Sparta, also, a form of selection was followed, for it was enacted that all children should be examined shortly after birth; the well-formed and vigorous being preserved, the others left to perish.13 If we consider all the races of man as forming a single species, his range is enormous; but some separate races, as the Americans and Polynesians, have very wide ranges. It is a well-known law that widely-ranging species are much more variable than species with restricted ranges; and the variability of man may with more truth be compared with that of widely-ranging species, than with that of domesticated animals. Not only does variability appear to be induced in man and the lower animals by the same general causes, but in both the same parts of the body are affected in a closely analogous manner. This, has been proved in such full detail by Godron and "With kine and horses, Kurnus! we proceed Wonder no more, my friend! the cause is plain, The Works of J. Hookham Frere, vol. ii. 1872, p. 354.) Quatrefages, that I need here only refer to their works." Monstrosities, which graduate into slight variations, are likewise so similar in man and the lower animals, that the same classification and the same terms can be used for both, as has been shewn by Laidore Geoffroy St.-Hilaire.15 In my work on the variation of domestic animals, I have attempted to arrange in a rude fashion the laws of variation under the following heads :--The direct and detinite action of changed conditions, as exhibited by all or nearly all the individuals of the same species, varying in the same manner under the same circumstances. The effects of the long-continued use or disuse of parts. The cohesion of homologous parts. The variability of multiple parts. Compensation of growth; but of this law I have found no good instance in the case of man. The effects of the mechanical pressure of one part on another; as of the pelvis on the cranium of the infant in the womb. Arrests of development, leading to the diminution or suppression of parts. The reappearance of long-lost characters through reversion. And lastly, correlated variation. All these so-called laws apply equally to man and the lower animals; and most of them even to plants. It would be superfluous here to discuss all of them;" but several are so important, that they must be treated at considerable length. .16 The direct and definite action of changed conditions.-This is a most perplexing subject. It cannot be denied that changed conditions produce some, and occasionally a considerable effect, on organisms of all kinds; and it seems at first probable that if sufficient time were allowed this would be the invariable result. But I have failed to obtain clear evidence in favour of this conclusion; and valid reasons may be urged on the other side, at least as far as the innumerable structures are concerned, which are adapted for special cnds. There can, however, be no doubt . that changed conditions induce an almost indefinite amount of fluctuating variability, by which the whole organisation is rendered in some degree plastic. In the United States, above 1,000,000 soldiers, who served in the late war, were measured, and the States in which they were 14 Godron, 'De l'Espèce,' 1859, tom. ii. livre 3. Quatrefages, Unite de l'Espèce Humaine,' 1861. Also Lectures on Anthropology, given in the Revue des Cours Scientifiques,' 1866-1868. 15 Hist. Gén. et Part. des Anomalies de l'Organisation,' in three volumes, tom. i. 1832. 16 I have fully discussed these laws in my 'Variation of Animals and Plants under Domestication,' vol. ii. chap. xxii. and xxiii. M. J. P. Durand has lately (1868) published a valuable essay 'De l'Influence des Milieux,' &c. He lays much stress, in the case of plants, on the nature of the soil. born and reared were recorded." From this astonishing number of observations it is proved that local influences of some kind act directly on stature; and we further learn that "the State "where the physical growth has in great measure taken place, "and the State of birth, which indicates the ancestry, seem to "exert a marked influence on the stature." For instance, it is established, "that residence in the Western States, during the "years of growth, tends to produce increase of stature." On the other hand, it is certain that with sailors, their life delays growth, as shewn "by the great difference between the statures of soldiers and sailors at the ages of seventeen and eighteen years." Mr. B. A. Gould endeavoured to ascertain the nature of the influences which thus act on stature; but he arrived only at negative results, namely, that they did not relate to climate, the elevation of the land, soil, nor even "in any controlling degree" to the abundance or the need of the comforts of life. This latter conclusion is directly opposed to that arrived at by Villermé, from the statistics of the height of the conscripts in different parts of France. When we compare the differences in stature between the Polynesian chiefs and the lower orders within the same islands, or between the inhabitants of the fertile volcanic and low barren coral islands of the same ocean,18 or again between the Fuegians on the eastern and western shores of their country, where the means of subsistence are very different, it is scarcely possible to avoid the conclusion that better food and greater comfort do influence stature. But the preceding statements shew how difficult it is to arrive at any precise result. Dr. Beddoe has lately proved that, with the inhabitants of Britain, residence in towns and certain occupations have a deteriorating influence on height; and he infers that the result is to a certain extent inherited, as is likewise the case in the United States. Dr. Beddoe further believes that wherever a race attains its maximum of physical development, it rises "highest in energy and moral vigour.' 66 " 19 Whether external conditions produce any other direct effect on man is not known. It might have been expected that dif ferences of climate would have had a marked influence, in as much as the lungs and kidneys are brought into activity under a low temperature, and the liver and skin under a high one." It was formerly thought that the colour of the skin and the character of the hair were determined by light or heat; and although it can hardly be denied that some effect is thus produced, almost all observers now agree that the effect has been very small, even after exposure during many ages. But this subject will be more properly discussed when we treat of the different races of mankind. With our domestic animals there are grounds for believing that cold and damp directly affect the growth of the hair; but I have not met with any evidence on this head in the case of man. Effects of the increased Use and Disuse of Parts.-It is well known that use strengthens the muscles in the individual, and complete disuse, or the destruction of the proper nerve, weakens them. When the eye is destroyed, the optic nerve often becomes atrophied. When an artery is tied, the lateral channels increase not only in diameter, but in the thickness and strength of their coats. When one kidney ceases to act from disease, the other increases in size, and does double work. Bones increase not only in thickness, but in length, from carrying a greater weight.21 Different occupations, habitually followed, lead to changed proportions in various parts of the body. Thus it was ascertained by the United States Commission 22 that the legs of the sailors employed in the late war were longer by 0.217 of an inch than those of the soldiers, though the sailors were on an average shorter men; whilst their arms were shorter by 109 of an inch, and therefore, out of proportion, shorter in relation to their lesser height. This shortness of the arms is apparently due to their greater use, and is an unexpected result: but sailors chiefly use their arms in pulling, and not in supporting weights. With sailors, the girth of the neck and the depth of the instep are greater, whilst the circumference of the chest, waist, and hips is less, than in soldiers. Whether the several foregoing modifications would become hereditary, if the same habits of life were followed during many generations, is not known, but it is probable. Rengger 23 attri butes the thin legs and thick arms of the Payaguas Indians to 20 Dr. Brakenridge, Theory of Diathesis,''Medical Times,' June 19 and July 17, 1869. 21 I have given authorities fər these several statements in my "Variation of Animals under Domestication,' vol. ii. pp. 297-300. Dr. Jaeger, "Ueber das Längen- 23 Säugethiere von Paraguay,' 1830, s. 4. |