VESTIGIAL ORGANS 257 



appears to be almost unlimited. We must remember, however, 

 that such modifications, in a state of nature at any rate, only 

 take place very slowly and gradually. 



Traces or vestiges of organs which have ceased to be of any 

 use to their possessors persist with astonishing pertinacity in 

 many organisms. Evidently their complete removal must be 

 an extremely slow process. We have already noticed the per- 

 sistence of vestiges of the pelvic girdle and leg bones in the 

 whale (Fig. 101), of the reduced metapodials or splint bones in 



FIG. 111. A New Zealand Kiwi, X &. (From a photograph of a stuffed 



specimen.) 



the feet of the horse (Fig. 97), and of the coracoid in the typical 

 mammalian shoulder girdle (Fig. 90). Unless we are to believe that 

 such structures have been put where they are on purpose to 

 mislead us we cannot possibly explain their occurrence on the 

 theory of special creation. They are, at any rate in many 

 cases, perfectly useless to their possessors, and the only rational 

 way of accounting for their presence is by supposing them 

 to be inherited from remote ancestors in which they were 

 functional. 



We may now briefly notice a few other instances of such 

 B, s 



