BREEDING. 
327 
a depth often of six feet, either in a perpendicular or 
oblique direction. Each gallery contained only a single 
egg, and was filled with loose sand, and it cost some labour 
to follow the direction of the tunnel and reach the end. 
Gilbert once met with a tumulus of this description, 
fifteen feet high and sixty in circumference, and found in 
one of the galleries only one egg. The singular mode 
of incubation adopted by this Gallinaceous bird is 
remarkable in two ways; for, on the one side, it is very 
extraordinary that a bird should bury its eggs in the 
ground like a reptile; and, on the other, it is almost 
incredible that so small a bird should be capable of 
erecting such a gigantic edifice. The power of maternal 
love, however, is all-powerful, and ever fertile in expe¬ 
dients. Of this fact I have found greater proofs in 
Africa than elsewhere. Take, as an example, the nest of 
the Pigmy Swift, I have already mentioned, which is 
built between the interstices of the palm leaves : it is 
flat, and the large broad leaves are often blown to and fro 
by the wind with great violence, so that the eggs and young 
might easily be thrown out; and yet this never happens. 
And why ? Maternal care has guarded against this great 
and foreseen danger—the bird sticks both eggs and 
young to the nest with her glutinous saliva; and thus 
they are safe. We shall, however, return to the subject of 
incubation. 
The time which elapses between the day the egg is 
laid and the appearance of the chick in the outer world, 
varies much with different species : the Goldcrest sits 
twelve days; the Swan, five weeks; the Humming-bird, 
probably, not over ten days, while the young Ostrich takes 
six times as long before it pierces the shell. And yet, one 
cannot always estimate the time by the size of the egg; 
