Morphology. 57 



as typical and not others ? Why should the vertebral 

 skeleton, for instance, be tortured into every conceiv- 

 able variety of modification in order to subserve as 

 great a variety of functions ; while another structure, 

 such as the eye, is made in different sub-kingdoms 

 on fundamentally different plans, notwithstanding 

 that it has throughout to perform the same function ? 

 Will any one have the hardihood to assert that in 

 the case of the skeleton the Deity has endeavoured 

 to show his ingenuity, by the manifold functions to 

 which he has made the same structure subservient ; 

 while in the case of the eye he has endeavoured to 

 show his resources, by the manifold structures which 

 he has adapted to serve the same function ? If so, 

 it becomes a most unfortunate circumstance that, 

 throughout both the vegetable and animal kingdoms, 

 all cases which can be pointed to as showing inge- 

 nious adaptation of the same typical structure to the 

 performance of widely different functions or cases 

 of homology without analogy, are cases which come 

 within the limits of the same natural group of plants 

 and animals, and therefore admit of being equally 

 well explained by descent from a common ancestry ; 

 while all cases of widely different structures per- 

 forming the same function or cases of analogy 

 without homology, are to be found in different 

 groups of plants or animals, and are therefore sug- 

 gestive of independent variations arising in the dif- 

 ferent lines of hereditary descent. 



To take a specific illustration. The octopus, or 

 devil-fish, belongs to a widely different class of animals 

 from a true fish ; and yet its eye, in general appear- 

 ance, looks wonderfully like the eye of a true fish. 



