436 INDEX 



Wings, evolution of, 136-7, 157 

 Winter sleep of animals, 55-7 

 Womb, development in the, 59-6 

 Wood-chat, song of the, 97 

 Woodpecker, the, 18,21 



noise of the, 96 



Work and play, 61 



,, mental and physical, 61-2 



World, infinity of the, 390 

 "Wren, the, 97 



Xylina vetusta, 193, 216 



YELLOW as warning colour, 147 

 Yolk of the egg, 247, 304 



ZOEA, 251 



THE END 



ttd by Cowan fr Co., Ltd., Perth. 



