54 THE THEORY OF EVOLUTION 



tubular form, and the former may be transformed 

 from jaws into piercing lancets. This arrangement 

 according to a definite rule, despite the differences 

 of form and use, finds its most probable explanation 

 in community of descent." l 



Examples of the same kind, drawn from all the 

 great divisions of the animal kingdom, might be in- 

 definitely multiplied, but such multiplication would 

 serve no useful purpose, even were it feasible within 

 our limits of time. The principle of numerous modi- 

 fications of a common plan, adapted to a great 

 variety of habits of life is made sufficiently clear by 

 the few instances already given. 



The objection has been frequently urged, just as in 

 the case of classification, that this diversification of 

 a single type of structure is no proof of a genetic 

 connection, or community of descent, but that the 

 connection is purely ideal, the manifestation of a 

 creative plan. The answer is the same in both 

 cases; acceptance of the theory of evolution by no 

 means excludes belief in a creative plan, but that 

 theory offers the most satisfactory solution of the 

 problem. Another and perhaps weightier objection 

 is that comparative anatomy gives us no means of 

 connecting animals of fundamentally different types 

 or plans of structure. It is impossible to derive a 

 fish from a lobster, or a starfish from an oyster and 

 thus the different structural types would seem to be 

 separated by impassable barriers. Evolution within 



1 Otto Maas, in Die Abstammungslehre, Jena, 1911, pp. 258-9. 



