43° 



The Bird 



reptilian horizon, and greatly altered all the conditions 

 of their life. The history of the egg of a bird, from the 

 time it is laid until it hatches, has an all-important effect 

 on its form, colour, and even upon the number of eggs 

 laid. This is not strange when we consider that every 

 minute of the bird's life is open to many dangers, and 

 that the egg stage — that bridging over of generations — 

 is a most precarious period. 



That which adds the greatest interest to anything is 

 the why of it, and a vast collection of eggs, beautiful 

 though they are, yet, if ignorantly looked at, is worse than 

 useless. Why one bird lays twenty eggs and another 

 but two; why one bird's eggs are white, another's of varied 

 colours, we will never learn from blown museum speci- 

 mens. Not until we have the patience and skill to watch 

 and to find the most deadly enemies which threaten the 

 nests and eggs of birds, their number and modes of attack, 

 can w^e hope for successful solutions to the thousand and 

 one problems which offer themselves. What we know in 

 respect to eggs is fragmentary and rests on so slight a 

 degree of proof that every theory is attacked and re- 

 attacked in turn. 



Supposing that the eggs of the early forms of birds 

 were round, — that being the most typical form of a single 

 cell, — we find many variations in shape among the eggs 

 of living species. Many of the eggs which are laid in 

 hollow trees still retain the primitive spherical form, per- 

 haps an advantage in keeping the eggs in a close group 

 in the centre of the floor of the cavit}'. 



So characteristic of the eggs of birds is the pear-shape 



