out the insult in a mortal duel. The whole thing is confined to
hostile demonstrations and a few insignificant cuffs.

Nevertheless, the real proprietress seems to derive double courage and
double strength from the feeling that she is in her rights. She takes
up a permanent position on the nest and receives the other, each time
that she ventures to approach, with an angry quiver of her wings, an
unmistakable sign of her righteous indignation. The stranger, at last
discouraged, retires from the field. Forthwith the Mason resumes her
work, as actively as though she had not just undergone the hardships
of a long journey.

One more word on these quarrels about property. It is not unusual,
when one Mason-bee is away on an expedition, for another, some
homeless vagabond, to call at the nest, take a fancy to it and set to
work on it, sometimes at the same cell, sometimes at the next, if
there are several vacant, which is generally the case in the old
nests. The first occupier, on her return, never fails to drive away
the intruder, who always ends by being turned out, so keen and
invincible is the mistress' sense of ownership. Reversing the savage
Prussian maxim, 'Might is right,' among the Mason-bees right is might,
for there is no other explanation of the invariable retreat of the
usurper, whose strength is not a whit inferior to that of the real
owner. If she is less bold, this is because she has not the tremendous
moral support of knowing herself in the right, which makes itself
respected, among equals, even in the brute creation.

The second of my travellers does not reappear, either on the day when
the first arrived or on the following days. I decide upon another
experiment, on this occasion with five subjects. The starting-place is