386 
GENERAL SUMMARY 
Part II. 
he retains, and the abnormal reversions to which he 
is occasionally liable, — are facts which cannot be dis- 
puted. They have long been known, but until recently 
they told us nothing with respect to the origin of 
man. Now when viewed by tlie light of our know- 
ledge of the whole organic world, their meaning is 
unmistakeable. The great principle of evolution stands 
up clear and firm, when these groups of facts are con- 
sidered in connection with others, such as the mutual 
affinities of the members of the same group, their 
geographical distribution in past and present times, 
and their geological succession. It is incredible that 
all these facts should speak falsely. He who is not 
content to look, like a savage, at the phenomena of 
nature as disconnected, cannot any longer believe that 
man is the work of a separate act of creation. He will 
be forced to admit that the close resemblance of the 
embryo of man to that, for instance, of a dog — the con- 
struction of his skull, limbs, and whole frame, indepen- 
dently of the uses to which the parts may bo put, on 
the same plan with that of other mammals — the occa- 
sional reappearance of various structures, for instance 
of several distinct muscles, which man does not nor- 
mally possess, but which are common to the Quadru- 
mana — and a crowd of analogous facts — all point in 
the plainest manner to the conclusion that man is the 
co-descendant with other mammals of a common pro- 
genitor. 
We have seen that man incessantly presents indi- 
vidual differences in all parts of his body and in his 
mental faculties. These differences or variations seem 
to be induced by the same general causes, and to obey 
the same laws as with the lower animals. In both 
cases similar laws of inheritance prevail. Man tends to 
increase at a greater rate than his means of subsistence ; 
