436 INDEX 



Wings, evolution of, 136-7, 157 World, infinity of the, 390 



Winter sleep of animals, 55-7 Wren, the, 97 



Womb, development in' the, 59-60 „ ,. 



Wood-chat, song of the, 97 ^V^*^ vetusta, 193, 216 



Woodpecker, the, 18, 21 Yellow as warning colour, 147 



w , " ^ , "°'^^^ °'^*^^' 9^ Yolk of the egg, 247, 304 

 Work and play, 61 ^**' ^" => ^ 



,, mental and physical, 61-2 Zoka, 251 



THE END 



Pr-.nicd by Cowar. &■ Co., Ltd., Perfi't. 



