Chap. XIV.] MORPHOLOGY. 235 



of the different parts or organs in the same individual, 

 and not of the same parts or organs in different mem- 

 bers of the same class. Most physiologists believe that 

 the bones of the skull are homologous — that is, cor- 

 respond in number and in relative connexion — with 

 the elemental parts of a certain number of vertebras. 

 The anterior and posterior limbs in all the higher verte- 

 brate classes are plainly homologous. So it is with 

 the wonderfully complex jaws and legs of crustaceans. 

 It is familiar to almost every one, that in a flower the 

 relative position of the sepals, petals, stamens, and pis- 

 tils, as well as their intimate structure, are intelligible 

 on the view that they consist of metamorphosed leaves, 

 arranged in a spire. In monstrous plants, we often get 

 direct evidence of the possibility of one organ being 

 transformed into another; and we can actually see, dur- 

 ing the early or embryonic stages of development in 

 flowers, as well as in crustaceans and many other ani- 

 mals, that organs, which when mature become extremely 

 different are at first exactly alike. 



How inexplicable are the cases of serial homologies 

 on the ordinary view of creation! Why should the 

 brain be enclosed in a box composed of such numerous 

 and such extraordinarily shaped pieces of bone, appa- 

 rently representing vertebrae? As Owen has remarked, 

 the benefit derived from the yielding of the separate 

 pieces in the act of parturition by mammals, will by 

 no means explain the same construction in the skulls 

 of birds and reptiles. Why should similar bones have 

 been created to form the wing and the leg of a bat, used 

 as they are for such totally different purposes, namely 

 flying and walking? Why should one crustacean, which 

 has an extremely complex mouth formed of many parts, 



