short, are "instinctive." Those with defective instincts 

 are forthwith killed by falling to the ground. They leave no 

 offspring to inherit their defects. 



Perhaps the most convincing evidence of all as to the 

 •' instinctive " nature of flight, in nesthng birds, is furnished 

 by the mound-birds, of the Malay Region and Eastern 

 Australia. 



These extraordinary birds lay their eggs in > heaps of 

 decajdng vegetable-matter, or in the soil near hot springs ; 

 and there leave them to their fate. They lay very large eggs, 

 it is to be noticed, so large that the growing chick finds 

 nourishment enough within the egg to enable it to pass the 

 ordinary nestling stage while still within the shell. By the 

 time it emerges it has both grown and shed its first coat of 

 nesthng-down, and has developed long wing-quills. Having 

 burst its prison walls it wriggles its way up through the loose 

 earth to the light of day, ready to fight its way in the world 

 unaided. Here, then, there can be no question of " teaching " 

 the young to fly. 



But some birds, at least, do, indeed^ receive instruction 

 when on the wing. And in such cases, it will be noticed, their 

 food can only be captured by dexterous movements in full 

 flight. For a day or two, for example, young swallows simply 

 practice flight, to exercise and strengthen their wings. They 

 are fed by their parents when at rest. The next step comes 



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