RUDIMENTARY STRUCTURES. 247 



covers to protect the delicate second pair which are 

 carefully folded beneath them. In the same class the 

 female glow-worm has, however, completely lost her 

 wings, although they are retained in a closely allied 

 Italian species. The fleas have both pairs of wings 

 represented merely by very small scales, which are' 

 thus typical rudimentary organs. 



We might go on indefinitely multiplying instances, 

 but those we have cited are sufficient to show that 

 rudimental structures must be regarded as the useless 

 relics or remnants of structures or organs that were 

 originally functional and useful ; their occurrence only 

 in the later and more specialised representatives of 

 individual groups at once traversing any contention 

 that might be raised as to their being the commence- 

 ments of organs which were subsequently to become 

 functional. 



In thus gradually tracing an organ or bone first to 

 its decadence, and then to its final rudimentary con- 

 dition or complete disappearance, we have before us 

 one of the most weighty pieces of evidence in sup- 

 port of the doctrine of evolution that can be adduced. 

 No hypothesis, indeed, but that of evolution can pos- 

 sibly offer any rational explanation of rudimentary 

 structures ; whereas this doctrine assigns a satisfac- 

 tory and definite reason for their existence. On the 

 old view of the separate creation of every species, the 

 existence of the useless, and to some extent harmful, 

 splint-bones in the horse's-foot is absolutely inex- 

 plicable in any way that will commend itself to a 



