402 The Outline of Science 



but in the living. The chicks are fully alive to the inconvenience 

 of being fought for by so many clumsy nurses, and I have seen 

 them not only make the best use of their legs in avoiding such 

 attentions, but remain to starve and freeze in preference to being 

 nursed. Undoubtedly, I think that of the 77 per cent, that die 

 before they shed their down, quite half are killed by kindness." 



3 



Flying Birds 



With this strange and rather terrible picture of the early life 

 of the Emperor Penguin amid the rigours of the Antarctic climate 

 and on the naked ice of the frozen sea, we may turn from flightless 

 to flying birds. The flightless birds, indeed, represent digressions 

 from the main line of descent, and cannot be regarded as 

 stages in the evolution of modern flying birds from the an- 

 cient forms which first mastered flight in the forests of long 

 ago. 



Birds share with mammals the distinction of being "warm- 

 blooded," that is to say, having a high and constant body tempera- 

 ture independent of surrounding conditions. We may take this 

 as an index of a high degree of vitality and of an advanced posi- 

 tion in the evolutionary scale, and we shall indeed find many other 

 features which lead towards the same conclusion. Birds are note- 

 worthy for alertness of mind and body, for quickness of move- 

 ment, and for their mastery of the air. They have highly 

 developed habits and complex instincts: they are in turn com- 

 bative, amatory, parental, cunning in pursuit and escape, and 

 in very many cases there is a surpassing beauty of plumage and 

 voice which compels our intense admiration. 



"Beast" is one of those words of variable and confused sense 

 which drive men of science to use a language of their own, but the 

 term "bird" scarcely needs to be defined, for its everyday meaning 

 is also scientifically accurate. This fact may perhaps be at- 

 tributed to the existence of certain very distinctive characteristics 



