that the Fuegians on board the Beagle were mistaken by some
Brazilians for Botocudos. The Botocudos again, as well as the other
inhabitants of tropical America, are wholly different from the Negroes
who inhabit the opposite shores of the Atlantic, are exposed to a
nearly similar climate, and follow nearly the same habits of life.
Nor can the differences between the races of man be accounted for by
the inherited effects of the increased or decreased use of parts,
except to a quite insignificant degree. Men who habitually live in
canoes, may have their legs somewhat stunted; those who inhabit lofty
regions may have their chests enlarged; and those who constantly use
certain sense-organs may have the cavities in which they are lodged
somewhat increased in size, and their features consequently a little
modified. With civilised nations, the reduced size of the jaws from
lessened use the habitual play of different muscles serving to express
different emotions and the increased size of the brain from greater
intellectual activity, have together produced a considerable effect on
their general appearance when compared with savages. (67. See Prof.
Schaaffhausen, translat., in Anthropological Review, Oct. 1868, p.
429.) Increased bodily stature, without any corresponding increase in
the size of the brain, may (judging from the previously adduced case of
rabbits), have given to some races an elongated skull of the
dolichocephalic type.
Lastly, the little-understood principle of correlated development has
sometimes come into action, as in the case of great muscular
development and strongly projecting supra-orbital ridges. The colour of
the skin and hair are plainly correlated, as is the texture of the hair
with its colour in the Mandans of North America. (68. Mr. Catlin states
( N. American Indians, 3rd ed., 1842, vol. i. p. 49) that in the whole
tribe of the Mandans, about one in ten or twelve of the members, of all
ages and both sexes, have bright silvery grey hair, which is
hereditary. Now this hair is as coarse and harsh as that of a horse s
mane, whilst the hair of other colours is fine and soft.) The colour
also of the skin, and the odour emitted by it, are likewise in some
manner connected. With the breeds of sheep the number of hairs within a
given space and the number of excretory pores are related. (69. On the
odour of the skin, Godron, Sur l Espece, tom. ii. p. 217. On the
pores in the skin, Dr. Wilckens, Die Aufgaben der Landwirth.
Zootechnik, 1869, s. 7.) If we may judge from the analogy of our
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