window, on a stone, or on a twig in some hedge, the Sicilian
Chalicodoma behaves in just the same way. For instance, should she
settle on a twig, the Bee begins by solidly cementing the base of her
cell to the slight foundation. Next, the building rises, taking the
form of a little upright turret. This first cell, when victualled and
sealed, is followed by another, having as its support, in addition to
the twig, the cells already built. From six to ten chambers are thus
grouped side by side. Lastly, one coat of mortar covers everything,
including the twig itself, which provides a firm mainstay for the
whole.


CHAPTER 2. EXPERIMENTS.

As the nests of the Mason-bee of the Walls are erected on small-sized
pebbles, which can be easily carried wherever you like and moved about
from one place to another, without disturbing either the work of the
builder or the repose of the occupants of the cells, they lend
themselves readily to practical experiment, the only method that can
throw a little light on the nature of instinct. To study the insect's
mental faculties to any purpose, it is not enough for the observer to
be able to profit by some happy combination of circumstances: he must
know how to produce other combinations, vary them as much as possible
and test them by substitution and interchange. Lastly, to provide
science with a solid basis of facts, he must experiment. In this way,
the evidence of formal records will one day dispel the fantastic
legends with which our books are crowded: the Sacred Beetle (A Dung-
beetle who rolls the manure of cattle into balls for his own
consumption and that of his young. Cf. "Insect Life", by J.H. Fabre,
translated by the author of "Mademoiselle Mori": chapters 1 and 2; and