entirely on eggs. It was calculated that not one egg in several hundred
was hatched out; yet in spite of such an extraordinary natural check the
islet was enormously overpopulated. Thousands of birds every year laid
eggs for the maintenance of fat and pompous reptiles, without reflecting
that there were other and lizardless isles on which the vital function of
incubation might be performed without loss. Years after other men of
science sought the isle. Birds seemed to be as numerous as ever, but the
lizards had disappeared. Had the birds been wise enough to perceive that
the plague of lizards had been sent as reproof for overcrowding, or did
the lizards become victims to physical deterioration incident upon
gluttony and sloth?

"Into every instinctive act there is an intrusion of reasoned act." No
doubt; but in the case of the terns--sea-frequenting and sea-loving--which
had not the wit to lay their eggs beyond the reach of spring tides, the
reasoning is the merest intrusion. Yet an instance of what seems to be
the reasoned act of a wasp may be cited. The insect had selected a dead
log of soft wood as a site for its egg-shaft. It was at a spot to which
the occupations of the season took me daily, so that the boring
operations were watched from beginning to end. The work was done rapidly
and neatly, and when all was ready for the deposit of the eggs the insect
constructed from papier-mache-like material a disc-shaped lid exactly
fitting the mouth of the excavation, to which it was attached on its
upper edge by a hinge. Then round and about the disc similar stuff was
plastered, so as to form an irregular splash, imitative of a bird's
droppings to the-degree of perfect deception. In the centre was the lid
with the hinge, and whensoever the insect visited its nursery the lid
swung up, closing behind it. On departure it fell into position. Unless
the insect by its presence betrayed its secret, the shrewdest observer at
close quarters would have been misled.