188 NATURAL SELECTION IX 
useless at the time when they first appeared, became in the 
highest degree useful at a much later period, and are now 
essential to the full moral and intellectual development of 
human nature, we should then infer the action of mind, 
foreseeing the future and preparing for it, just as surely as 
we do, when we see the breeder set himself to work with the 
determination to produce a definite improvement in some culti- 
vated plant or domestic animal. I would further remark that 
this inquiry is as thoroughly scientific and legitimate as that 
into the origin of species itself. It is an attempt to solve 
the inverse problem, to deduce the existence of a new power 
of a definite character, in order to account for facts which, 
according to the theory of natural selection, ought not to 
happen. Such problems are well known to science, and the 
search after their solution has often led to the most brilliant 
results. In the case of man, there are facts of the nature 
above alluded to, and in calling attention to them, and in 
inferring a cause for them, I believe that I am as strictly 
within the bounds of scientific investigation as I have been 
in any other portion of my work. 
The Brain of the Savage shown to be Larger than he Needs it to be 
Size of Brain an important Element of Mental Power.— The 
brain is universally admitted to be the organ of the mind; 
and it is almost as universally admitted that size of brain is 
one of the most important of the elements which determine 
mental power or capacity. There seems to be no doubt that 
brains differ considerably in quality, as indicated by greater 
or less complexity of the convolutions, quantity of gray 
matter, and perhaps unknown peculiarities of organisation ; 
but this difference of quality seems merely to increase or 
diminish the influence of quantity, not to neutralise it. 
Thus, all the most eminent modern writers see an intimate 
connection between the diminished size of the brain in the 
lower races of mankind, and their intellectual inferiority. 
The collections of Dr. J. B. Davis and Dr. Morton give the 
following as the average internal capacity of the cranium in 
the chief races: Teutonic family, 94 cubic inches ; Esquimaux, 
91 cubic inches; Negroes, 85 cubic inches; Australians and Tas- 
manians, 82 cubic inches; Bushmen, 77 cubic inches. These 
