EGGS AND EQQ-COLIECTINO 13 



a wonderful adaptability to the exposed situation chosen 

 by this bird for incubation. 



Birds which make round, cup-shaped nests, or incubate 

 in holes, such as the Owl and Kingfisher, for instance, 

 lay round eggs, which run no risk of rolling away and 

 being smashed. Their shape also facilitates alteration of 

 position of the parent-bird to secure an equal distribution 

 of warmth and ventilation. 



Were the Guillemot and either of the latter birds to 

 change nesting situations for a while, it is probable a 

 speedy extermination of the species which adopted the flat 

 rock for the round egg would soon take place, affording a 

 beautiful illustration of the power that is also guiding the 

 action of birds under the mysterious name of instinct. 

 It is an unknown and unknowable power, yet its workings 

 are as undeniable as its results. 



As a further illustration, let us take the eggs of the 

 Golden and Green Plovers, and consider for a moment 

 their size, shape, number, and colour. 



All these qualities serve some well-defined and demons- 

 trably useful end. Firstly, their size is abnormally large 

 compared with that of the layer, but this is a provision 

 which supplies the necessary size and strength of the 

 young bird to enable it to cope with the surrounding con- 

 ditions of its first days of self-feeding and locomotion 

 amongst coarse grass and other obstacles. 



Secondly, the shape of the egg serves to economise space, 

 an important point where the eggs are large and the bird 

 small. Thus the four pear-shaped eggs, having their small 

 ends all pointing to a common centre, practically form a 

 square, and thus enable the bird to cover them all at the 

 same time. 



