IX.] RETROGRESSIVE DEVELOPMENT IN NATURE. 29 



gressive, now concerned with the development of a single 

 structure, and now of a whole organism. Everything that 

 nature has built up with such elaborate care— highly-developed 

 organs of locomotion, limbs fitted to support a certain weight, 

 joints with their complex and yet easy movements, the exquisite 

 balance of muscular strength required for rapid motion on the 

 ground, wings adapted for flying, with all the marvellously 

 adjusted organs which overcome gravity and render rising into 

 the air a possibilit}^, every one of the adaptations by which 

 animals are placed in communication with the outer world 

 which surrounds them, — eyes of the most delicate and complex 

 structure, organs of hearing and smell so wonderfully formed 

 that it has needed long years of the combined researches of all 

 the most eminent naturalists to understand their full signi- 

 ficance—each one of these is relinquished, is handed over to a 

 process of gradual destruction, the moment it ceases to be 

 essential to the life of the species. 



It would indeed seem as if such a process of development 

 could not justly be called progress, and as far as the individual 

 organ undergoing degeneration is concerned the process is of 

 course retrogressive ; but the case becomes different when we 

 regard the organism as a whole. For the end and purpose of 

 all living beings is after all but the existence of each individual : 

 the form assumed, the complexity of structure, the degree of 

 perfection, are all quite immaterial provided that the species be 

 fit to survive : less than fit it cannot be, or it succumbs, neither 

 can it be more so, because no means exist which can enable 

 it to rise be3rond the point of fitness necessary for survival. 

 Schopenhauer's pessimistic view that the world was as bad as 

 it could be, and that, if it could grow in the least degree worse, 

 it would be annihilated altogether, might be reversed and con- 

 verted into an optimistic one : for it would be equally true to 

 say that the world is as excellent as it is possible to make it 

 WMth the given materials, and that a nearer approach to absolute 

 perfection is inconceivable. The organic world teaches us 

 that such is the case ; each existing species shows the purpose 

 of its being in every detail of its structure, and in its perfect 

 adaptation to the conditions under which it lives. But it is 

 only adapted so far as is actually necessary, only so far as to 

 make it fittest to survive, and not a step further. The eye of 



