432 The Bird 
shape of egg, serving in these instances a very apparent 
and useful end. These birds almost invariably lay four 
eggs, which are of large size in comparison with the birds, 
and their shape allows them to be fitted closely together, 
each forming one of the four segments, their points all 
but meeting in the centre. Thus the little body of the 
Fig. 344.—Eggs of Killdeer. 
parent is large enough to cover them all, which would be 
impossible were the eggs arranged at random. The eggs 
of grebes are peculiar in having both ends alike. 
The number of eggs which a bird lays has been found 
to bear a definite relation to the amount of danger to 
which the species is exposed—a fact which holds good 
