for existence, and consequently to natural selection. He has given rise
to many races, some of which differ so much from each other, that they
have often been ranked by naturalists as distinct species. His body is
constructed on the same homological plan as that of other mammals. He
passes through the same phases of embryological development. He retains
many rudimentary and useless structures, which no doubt were once
serviceable. Characters occasionally make their re-appearance in him,
which we have reason to believe were possessed by his early
progenitors. If the origin of man had been wholly different from that
of all other animals, these various appearances would be mere empty
deceptions; but such an admission is incredible. These appearances, on
the other hand, are intelligible, at least to a large extent, if man is
the co-descendant with other mammals of some unknown and lower form.
Some naturalists, from being deeply impressed with the mental and
spiritual powers of man, have divided the whole organic world into
three kingdoms, the Human, the Animal, and the Vegetable, thus giving
to man a separate kingdom. (1. Isidore Geoffroy St.-Hilaire gives a
detailed account of the position assigned to man by various naturalists
in their classifications: Hist. Nat. Gen. tom. ii. 1859, pp.
170-189.) Spiritual powers cannot be compared or classed by the
naturalist: but he may endeavour to shew, as I have done, that the
mental faculties of man and the lower animals do not differ in kind,
although immensely in degree. A difference in degree, however great,
does not justify us in placing man in a distinct kingdom, as will
perhaps be best illustrated by comparing the mental powers of two
insects, namely, a coccus or scale-insect and an ant, which undoubtedly
belong to the same class. The difference is here greater than, though
of a somewhat different kind from, that between man and the highest
mammal. The female coccus, whilst young, attaches itself by its
proboscis to a plant; sucks the sap, but never moves again; is
fertilised and lays eggs; and this is its whole history. On the other
hand, to describe the habits and mental powers of worker-ants, would
require, as Pierre Huber has shewn, a large volume; I may, however,
briefly specify a few points. Ants certainly communicate information to
each other, and several unite for the same work, or for games of play.
They recognise their fellow-ants after months of absence, and feel
sympathy for each other. They build great edifices, keep them clean,
close the doors in the evening, and post sentries. They make roads as
well as tunnels under rivers, and temporary bridges over them, by
163