ORGANIC EVOLUTION— THE FACTORS 111 



move them are also enlarged, nothing will be gained. 

 Such modification of the neck will be useless, or rather 

 will be detrimental, if its fulcrum be not made capable 

 of resisting intense strains ; the upjDer dorsal vertebrae 

 and their spines must be strengthened, that they may 

 withstand the more violent contraction of the neck 

 muscles; and like changes must be made on the 

 scapular arch; still more must there be required a 

 simultaneous development of the bones and muscles of 

 the fore-legs," &.c.—Frinciplcs of Biology, vol. i. 



Such, as briefly but as fairly as I am able to give 

 them, are Mr. Sj^encer's arguments. They are set 

 forth at great length in the pamphlet we have under 

 consideration, and in his book, the Fmicijjles of Biologt/, 

 from which the quotation given above is taken. 

 Examined closely, we find that they are nearly the 

 same arguments, but much amplified, as those already 

 dealt with, whereby he sought to prove that accumu- 

 lation of inborn variations is not alone sufficient to 

 account for the evolution of any given quality (r, y. 

 sight, scent, hearing, speed, &c., each of which depends 

 on the functional activity of a group of structures), on 

 the ground that if one animal survived because of 

 superior keenness of sight, and others survived because 

 of superior powers of scent, or hearing, or speed, or 

 agility, or digestion respectively, then, since the qualities 

 essential to survival are numerous, the several superior- 

 ities would be cancelled by interbreeding, and in the 

 end there would be no evolution. He forgot, as we 

 saw, that the essential qualities are not found dis- 

 associated, keenness of sight in one deer, keenness of 

 hearing in another, and so forth ; and moreover, that 

 excellence in one quality is not unusually accompanied 

 by excellence in other qualities, the vigorous in one 

 respect being usually vigorous in other respects as well. 



