cientiously stopping up the entrance to a tube or a Snail-shell in
which they have laid nothing at all. Others are closing the home after
only building a few partitions, or even mere attempts at partitions.
Some are placing at the back of a new gallery a pinch of pollen which
will benefit nobody and then shutting up the house with an earthen
stopper as thick, as carefully made as though the safety of a family
depended on it. Born a worker, the Osmia must die working. When her
ovaries are exhausted, she spends the remainder of her strength on
useless works: partitions, plugs, pollen-heaps, all destined to be left
unemployed. The little animal machine cannot bring itself to be inactive
even when there is nothing more to be done. It goes on working so that
its last vibrations of energy may be used up in fruitless labour. I
commend these aberrations to the staunch supporters of reasoning-powers
in the animal.

Before coming to these useless tasks, my laggards have laid their last
eggs, of which I know the exact cells, the exact dates. These eggs, as
far as the microscopes can tell, differ in no respect from the others,
the older ones. They have the same dimensions, the same shape, the same
glossiness, the same look of freshness. Nor are their provisions in
any way peculiar, being very well suited to the males, who conclude the
laying. And yet these last eggs do not hatch: they wrinkle, fade and
wither on the pile of food. In one case, I count three or four sterile
eggs among the last lot laid; in another, I find two or only one.
Elsewhere in the swarm, fertile eggs have been laid right up to the end.

Those sterile eggs, stricken with death at the moment of their birth,
are too numerous to be ignored. Why do they not hatch like the other
eggs, which outwardly they resemble in every respect? They have received
the same attention from the mother and the same portion of food. The
searching microscope shows me nothing in them to explain the fatal
ending.

To the unprejudiced mind, the answer is obvious. Those eggs do not hatch
because they have not been fertilized. Any animal or vegetable egg that
had not received the life-giving impregnation would perish in the same
way. No other answer is possible. It is no use talking of the distant
period of the laying: eggs of the same period laid by other mothers,
eggs of the same date and likewise the final ones of a laying, are
perfectly fertile. Once more, they do not hatch because t