52 CLASSIFICATION AND CREATION. 



Birds, wings are a typical feature, corresponding 

 to the front limbs in all Vertebrates, which are 

 constructed in the same way, whether they are 

 arms as in Man, or fore-legs as in Quadrupeds, or 

 pectoral fins as in Fishes, or wings as in Birds. 

 The wing in an Insect, on the contrary, is a 

 flattened, dried-up gill, having no structural re- 

 lation whatever to the wing of a Bird. They 

 are analogous only, because they resemble each 

 other in form and in function, being in the same 

 way subservient to flight; but as organs they 

 are entirely different. The wings of Birds are 

 homologous to the limbs of other Vertebrates, 

 notwithstanding their great apparent difference ; 

 they are only analogous to the wings of Insects, 

 notwithstanding their great external resemblance. 

 In adding Infusoria to the Radiates, Cuvier 

 was false to his own principle of founding all 

 classification on plan. He was influenced by- 

 their seeming simplicity of structure, and placed 

 them in the lowest division of the Animal King- 

 dom on that account. But even this simplicity 

 was only apparent in many of them. At cer- 

 tain seasons of the year myriads of these little 

 Animalcules may be seen in every brook and 

 road-side pool. They are like transparent little 

 globules, without any special organization, appar- 

 ently ; and were it not that they are in constant 

 rotation, exhibiting thus a motion of their own, 



