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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