CHAP. XVI Backboned Animals 265 



flame : it rests upon the air, subdues it, surpasses it, outraces it ; — 

 is \he. air, conscious of itself, conquering itself, ruling itself." 



Birds represent among animals the climax of activity, an index to 

 which may be found in their high temperature, from 2°- 14° Fahren- 

 heit higher than that of mammals. In many other ways they lank 

 high, for whether we consider the muscles which move the wings 

 in flight, the skeleton which so marvellously combines strength 

 with lightness, the breathing powers perfected and economised by a 

 set of balloons around the lungs, or the heart which drives and 

 receives the warm blood, we recognise that birds share with 

 mammals the position of the highest animals. And while it is true 

 that the brains of birds are not wrinkled with thought like 

 those of mammals, and that the close connection between motlier 

 and offspring characteristic of most mammals is absent in birds, it 

 may be urged by those who know their joyousness that birds feel 

 more if they think less, while the patience and solicitude con- 

 nected with nest-making and brooding testify to the strength of 

 their parental love. Usually living in varied and beautiful sur- 

 roundings, birds have keen eyes and sharp ears, tutored to a sense 

 of beauty, as we may surely conclude from their cradles and love 

 songs. They love much and joyously, and live a life remarkably 

 free and restless, qualities symbolised by the voice of the air in 

 their throat, and by the sunshine of their plumes. There is more 

 than zoological truth in saying that in the bird " the breath or spirit 

 is more full than in any other creature, and the earth power least," 

 or in thinking of birds as the purest embodiments of Athene of 

 the air. 



But just as there are among mammals feverish bats with the power 

 of true flight, and whales somewhat fish-like, so there are excep- 

 tional birds, runners like the ostriches and cassowaries, swimmers 

 like the penguins, criminals too like the cuckoos and cow-birds in 

 which the maternal instincts are strangely perverted. As we go 

 back into the past, strange forms are discovered, with teeth, long 

 tails, and other characteristics which link the birds of the air to the 

 grovelling reptiles' of the earth. Even to-day there lives a 

 "reptilian-bird" — Opisthocotnus — which has retained moie than 

 any other indisputable affinities with the reptiles. Professor W. K. 

 Parker, one of the profoundest of all students of birds, described 

 this form in one of his last papers, and there used a comparison 

 which helps us to appreciate birds. They are among backboned 

 animals what insects are among the backboneless — winged pos- 

 sessors of the air, and just as many insects pass through a cater- 

 pillar and chrysalis stage before reaching the acme of their life as a 

 flying imago, so do the young birds within the veil of the egg- 

 shell pass through somewhat fish-like and somewhat reptile-like 



