TilE ARGUMEXTS FROM MORPHOLOGY. 381 



other; yet they are indentifiable as homologous with 

 segments, which, in other crustaceans, are definitely 

 divided. AYhat, now, can be the meaning of this 



community of structure among these hundreds of thousands of 

 species filling the air, burrowing in the earth, swimming in 

 the water, creei)ing about among the sea- weed, and having 

 such enormous differences of size, outline, and substance, as 

 that no community would be suspected between them ? "Why 

 under the down-covered body of the moth and under the 

 hard wing-cases of the beetle, should there be discovered the 

 same niunber of divisions as in the calcareous framework of 

 the lobster ? It cannot be by chance that there exist just 

 twenty segments in all these hundreds of thousands of species. 

 There is no reason to think it was necessary, in the sense 

 that no other number would have made a possible organism. 

 And to say that it is the result of design — to say that the Cre- 

 ator followed this pattern throughout, merely for the purpose 

 of maintaining the pattern — is to assign a motive which, if 

 avowed by a human being, we should call whimsical. No 

 rational interpretation of this and hosts of like morphological 

 truths, can be given except by the hypothesis of evolution ; 

 and from the hj^othesis of evolution they are corollaries. 

 If organic forms have arisen from common stocks by per- 

 petual divergences and redivergences — ^if they have continued 

 to inherit, more or less clearly, the characters of ancestral 

 races; then there will naturally result these communities of 

 fundamental structure among extensive assemblages of crea- 

 tures, that have severally become modified in countless ways 

 and degrees, in adaptation to their respective modes of 

 life. To this let it be added, that while the belief 



in an intentional adhesion to a pre-determined pattern 

 throughout a whole group, is totally negatived by the occur- 

 rence of occasional deviations from the pattern ; such devi- 

 ations are reconcilable with the beKef in evolution. As 

 pointed out in the last chapter, there is reason to think that 

 remote ancestral traits, will be obscured more or less according 



