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simple reason that, as may be concluded from what has 
been already said respecting cranial capacity, the difference 
in weight of brain between the highest and the lowest men is 
far greater, both relatively and absolutely, than that between 
the lowest man and the highest ape. The latter, as has been 
seen, is represented by, say twelve, ounces of cerebral sub- 
stance absolutely, or by 32: 20 relatively ; but as the largest 
recorded human brain weighed between 65 and 66 ounces, 
the former difference is represented by more than 33 ounces 
absolutely, or by 65 : 32 relatively. Regarded systematically 
the cerebral differences, of man and apes, are not of more than 
generic value—his Family distinction resting chiefly on his 
dentition, his pelvis, and his lower limbs. 
Thus, whatever system of organs be studied, the comparison 
of their modifications in the ape series leads to one and the 
same result—that the structural differences which separate 
Man from the Gorilla and the Chimpanzee are not so great 
as those which separate the Gorilla from the lower apes. 
of dumb associates. And yet there might not be the slightest discernible dif- 
ference between his brain and that of a highly intelligent and cultivated person. 
The dumbness might be the result of a defective structure of the mouth, or of 
the tongue, or amere defective innervation of these parts; or it might result from 
congenital deafness, caused by some minute defect of the internal ear, which 
only a careful anatomist could discover. 
The argument, that because there is an immense difference between a Man's 
intelligence and an Ape’s, therefore, there must be an equally immense difference 
between their brains, appears to me to be about as well based as the reasoning 
by which one should endeavour to prove that, because there is a “great gulf” 
between a watch that keeps accurate time and another that will not go at all, 
there is therefore a great structural hiatus between the two watches. A hair 
in the balance-wheel, a little rust on a pinion, a bend in a tooth of the escapement, 
a something so slight that only the practised eye of the watchmaker can discover 
it, may be the source of all the difference. 
And believing, as I do, with Cuvier, that the possession of articulate speech is 
the grand distinctive character of man (whether it be absolutely peculiar to him 
or not), I find it very easy to comprehend, that some equally inconspicuous struc- 
tural difference may have been the primary cause of the immeasurable and prac- 
tically infinite divergence of the Human from the Simian Stirps. 
