282 MISCELLANEOUS OBJECTIONS TO THE [Chap. VTL 



throughly aquatic as to brave the open ocean. But 

 seals would not find on oceanic islands the conditions 

 favourable to their gradual reconversion into a terrestrial 

 form. Bats, as formerly shown, probably acquired their 

 wings bv at first gliding through the air from tree to 

 tree, like the so-called flying squirrels, for the sake of 

 escaping from their enemies, or for avoiding falls ; but 

 when the power of true flight had once been acquired, it 

 would never be reconverted back, at least for the above 

 purposes, into the less efficient power of gliding through 

 the air. Bats might, indeed, like many birds, have had 

 their wings greatly reduced in size, or completely lost, 

 through disuse ; but in this case it would be necessary 

 that they should first have acquired the power of running 

 quickly on the ground, by the aid of their hind legs alone, 

 so as to compete with birds or other ground animals ; and 

 for such a change a bat seems singularly ill-fitted. These 

 conjectural remarks have been made merely to show that 

 a transition of structure, with each step beneficial, is a 

 highly complex affair ; and that there is nothing strange 

 in a transition not having occurred in any particular case. 

 Lastly, more than one writer has asked, why have 

 some animals had their mental powers more highly de- 

 veloped than others, as such development would be 

 advantageous to all ? Why have not apes acquired the 

 intellectual powers of man ? Various causes could be 

 assigned ; but as they are conjectural, and their relative 

 probability cannot be weighed, it would be useless to 

 give them. A definite answer to the latter question 

 ought not to be expected, seeing that no one can solve 

 the simpler problem why, of two races of savages, one has 

 risen higher in the scale of civilisation than the other ; 

 and this apparently implies increased brain-power. 



