THE INSURGENCE OF LIFE 149 



these are interesting, the majority are not, since we are apt 

 to forget that the bird does not know what hats and sleeves 

 and lamps are. In many cases, moreover, these divergences 

 prove dismal failures. We refer rather to cases hke the 

 nesting of the White Tern [Gygis alba), one of the most 

 interesting and beautiful birds of Norfolk Island in the 

 Western Pacific, about nine hundred and fifty miles north- 

 east from Sydney. The bird breeds in densely wooded gulUes, 

 and it lays its single egg in a knot-hole or any shght depres- 

 sion on a more or less horizontal branch. It is difficult to 

 think of any more hazardous situation. Mr. A. F. Basset 

 HuU tells us that ' the sitting bird puffs out its breast- 

 feathers so as to completely hide the egg, depressing its 

 forked tail so as to obtain as secure a hold as possible, and 

 sits with its beak pointing into the eye of the wind, so as 

 to offer the least resistance '. Both parents share in the 

 task of incubation, and we are not surprised to learn that 

 they show great caution in rising and settling. It is the 

 place chosen for the egg that chiefly concerns us, but we 

 may finish Mr. Hull's interesting story. 



' I saw the young bird, a ball of black down, squatting 

 unconcernedly on the bare Kmb while its parents were away 

 searching for food. A week later it was still there, and had 

 then grown nearly as large as its mother, but it was stiU 

 covered with the black down. Its mother flew up, and 

 straddled over it, vainly endeavouring to cover it. There it 

 sat blinking down at us, like a black piccaninny in the 

 arms of a white nurse.' 



Tadpoles of a Tree Frog. — To illustrate a cluster of 

 adaptations, let us take Dr. W. E. Agar's account of the 

 nest made by one of the tree-frogs, Phyllomedusa sauvagii. 

 The adults are arboreal in their habits, and yet the tadpoles 



