CHAPTER XIV 



BIRDS AND INSECTS : AS PROOFS OF AN OKGANISING AND 



DIRECTIVE LIFE-PRINCIPLE 



If we strip a bird of its feathers so that we can see its bodj- 

 structure as it really is, it appears as the most ungainly and 

 misshapen of living creatures ; yet there is hardly a bird but 

 in its natural garment is pleasing in its form and motions, 

 while a large majority are among the most beautiful in shape 

 and proportions, the most graceful in their activities, and often 

 the most exquisite and fascinating of all the higher animals. 

 The fact is, that the feathers are not merely a surface-clothing 

 for the body and limbs, as is the hairy covering of most mam- 

 mals, but in the wing and tail-feathers form an essential part 

 of the structure of each species, without which it is not a com- 

 plete individual, and could hardly maintain its existence for 

 a single day. The whole internal structure has been gradually 

 built up in strict relation to this covering, so that every part 

 of the skeleton, every muscle, and the whole of the vascular 

 system for blood-circulation and aeration have been slowly 

 modified in such close adaptation to the whole of the plumage 

 that a bird without its feathers is almost as helpless as a mam- 

 mal which has lost its limbs, tail, and teeth. 



Although birds are so highly organised as to rival mam- 

 ' mals in intelligence, while they surpass them in activity and 

 in their high body -temperature, yet they owe this position to 

 an extreme retrogressive specialisation resulting in the com- 

 plete loss of the teeth, while the digits of the fore limb are re- 

 duced to three, the bones of which are more or less united, and, 

 though slightly movable, are almost entirely hidden under tho 

 skin. 



The earliest fossil bird, the Arch^eopteryx, bad throe ap- 



301) 



