with a geographical sense of which the Swallow, the Martin and the
Carrier-pigeon would not have been ashamed; and you would have asked
yourself, as I did, what incomprehensible knowledge of the local map
guides that mother seeking her nest.

To come to facts: it is a matter of repeating with the Mason-bee of
the Walls my former experiments with the Cerceris-wasps (Cf. "Insect
Life": chapter 19.--Translator's Note.), of carrying the insect, in
the dark, a long way from its nest, marking it and then leaving it to
its own resources. In case any one should wish to try the experiment
for himself, I make him a present of my manner of operation, which may
save him time at the outset. The insect intended for a long journey
must obviously be handled with certain precautions. There must be no
forceps employed, no pincers, which might maim a wing, strain it and
weaken the power of flight. While the Bee is in her cell, absorbed in
her work, I place a small glass test-tube over it. The Mason, when she
flies away, rushes into the tube, which enables me, without touching
her, to transfer her at once into a screw of paper. This I quickly
close. A tin box, an ordinary botanizing-case, serves to convey the
prisoners, each in her separate paper bag.

The most delicate business, that of marking each captive before
setting her free, is left to be done on the spot selected for the
starting-point. I use finely-powdered chalk, steeped in a strong
solution of gum arabic. The mixture, applied to some part of the
insect with a straw, leaves a white patch, which soon dries and
adheres to the fleece. When a particular Mason-bee has to be marked so
as to distinguish her from another in short experiments, such as I
shall describe presently, I confine myself to touching the tip of the
abdomen with my straw while the insect is half in the cell, head