32 DEGENERATION. 



important organs, so that not only the legs, but the 

 organs of sense, the nervous system, and even the 

 mouth and digestive organs are obliterated — then we 

 shall have pictured a thorough-going instance of 

 Degeneration. 



Degeneration may be defined as a gradual change 

 of the structure in which the organism becomes 

 adapted to less varied and less complex conditions 

 of life ; whilst Elaboration is a gradual change of 

 structure in which the organism becomes adapted 

 to more and more varied and complex conditions of 

 existence. In Elaboration there is a new expression 

 of form, corresponding to new perfection of work in 

 the animal machine. In Degeneration there is stip- 

 pression of form, corresponding to the cessation of 

 work. Elaboration of some one organ may be a 

 necessary accompaniment of Degeneration in all the 

 others ; in fact, this is very generally the case ; and it 

 is only when the total result of the Elaboration of 

 some organs, and the Degeneration of others, is such 

 as to leave the whole animal in a lower condition, 

 that is, fitted to less complex action and reaction in 

 regard to its surroundings, than was the ancestral 

 form with which we are comparing it (either actually 



