The Making of Species 
animal are widely different from the forces acting 
upon an animal which eats the grass at its feet 
like an ox, or one which must run and climb like 
a goat or a deer, and the resultant modifications 
of growth in the several cases must also be 
different. The principle of increased growth in 
the direction of the shock, resulting from super- 
abundant repair of the momentary compression, 
explains how the giraffe acquired the phenomenal 
length of the bones of its forelegs and neck ; 
and the absence of the shock in the hind-quarters 
shows why they remained undeveloped and 
absurdly disproportionate to the rest of the 
body.” 
It seems to us that a fatal objection to all 
these Neo-Lamarckian theories of evolution is 
that they are based on the assumption that 
acquired characters are inherited, whereas all 
the evidence goes to show that such characters 
are not inherited. In these days, when scientific 
knowledge is so widely diffused, it is scarcely 
necessary to say that all the characteristics which 
an organism displays are either congenital or 
inborn, or acquired by the organism during its 
lifetime. Thus a man may have naturally a 
large biceps muscle, and this is a congenital 
character; or he may by constant exercise 
develop or greatly increase the size of the 
biceps. The large biceps, in so far as it has 
been increased by exercise, is said to be an 
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