538 THE EVOLUTION OF LIFE. 



ened as to impress more force on them, and to bear the more 

 violent reactions of the blows given. The bones of the skull 

 on which the horns are seated must be thickened; otherwise 

 they will break. The vertebras of the neck must be further 

 developed; and unless the ligaments which hold together 

 these vertebra?, and the muscles which move them, are also 

 enlarged, nothing will be gained. Again the upper dorsal 

 vertebra? and their spines must be strengthened, that they 

 may withstand the stronger contractions 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; since these extra 

 growths in the horns, in the skull, in the neck, in the 

 shoulders, add to the burden they have to bear; and without 

 they are strengthened the creature will not only suffer from 

 loss of speed but will fail in fight. Hence, to make larger 

 horns of use, additional sizes must be acquired by numerous 

 bones, muscles, and ligaments, as well as by the blood-ves 

 sels and nerves on which their actions depend. On call 

 ing to mind how the spraining of a single small muscle in 

 the foot incapacitates for walking, or how permanent weak 

 ness in a knee-ligament will diminish the power of the leg, 

 it will be seen that unless all these many changes are simul 

 taneously made, they may as well be none of them made 

 or rather, they would better be none of them made; since 

 the enlargements of some parts, by putting greater strains 

 on connected parts, would render them relatively weaker if 

 they remained unenlarged. Can we with any propriety 

 assume that these many enlargements duly proportioned will 

 be simultaneously effected by spontaneous variations? I 

 think not. It would be a strong supposition that the verte 

 bra? and muscles of the neck suddenly became bigger at the 

 same time as the horns. It would be a still stronger sup 

 position that the upper dorsal vertebra? not only at the same 

 time became more massive, but appropriately altered their 

 proportions^ by the development of their immense neural 



