Disease is commonly accompanied by a change of colour. Mr. Wallace observes that, in many islands of the Malay Archipelago, species of widely different genera of butterflies differ in precisely the same way as to colour or form from allied species in other islands.[1605] The same thing occurs to a less degree in other parts of the world also. And Agassiz has pointed out that, in Asia and Africa, the large apes and the human races have the same colour of the skin.[1606] We may thus take for granted that racial peculiarities stand in some connection with the external circumstances in which the various races live. It may perhaps be objected that we meet with native tribes of various types on the same degree of latitude, and under the same climatic conditions.[1607] But we must remember that it is often impossible to decide whether the conditions of life are exactly the same; that intermixture of blood has caused a great confusion of racial types; and that all peoples have arrived at their present localities after more or less extensive migrations. We may be sure that some characters have been preserved from earlier times when the race lived in other circumstances, and that the higher its degree of civilization the less likely it would be to lose the stamp impressed upon it.[1608] It is, however, exceedingly doubtful whether racial differences are so directly the result of external influences as anthropologists generally believe,—that is, whether they are the inherited effects of conditions of life to which previous generations have been subject. Professor Weismann, as is well known, thinks that acquired characters are not transmitted from parent to offspring. “It has never been proved,” he says, “that acquired characters are transmitted, and it has never been demonstrated that, without the aid of such transmission, the evolution of the organic world becomes unintelligible.”[1609] Man has from time immemorial mutilated his body in various ways, and there is not a single well-founded case of these mutilations having been inherited by the offspring.[1610] The children of accomplished pianists do not inherit the art of playing the piano. Facts show that children of highly civilized nations have no trace of a language, when they have grown up in a wild condition and in complete isolation.[1611] Change in colour influenced by sun and air is obviously temporary. The children of the husbandman, or of the sailor, are just as fair as those of the most delicate and pale inhabitant of a city; and, although the Moors, who have lived in Africa since the seventh century, are generally in mature life very sunburnt, their children are as white as those born in Europe, and “restent blancs toute leur vie, quand leurs travaux ne les exposent pas aux ardeurs du soleil.”[1612]