the open, I see the Wasp proceed to separate the succulent from
the tough; I see her reject the legs, the wings, the head and the
abdomen, retaining only the breast as pap for her larvae. Then what
value has this dissection as an argument in favour of the insect's
reasoning-powers when the wind blows? It has no value at all, for it
would take place just the same in absolutely calm weather. Erasmus
Darwin jumped too quickly to his conclusion, which was the outcome of
his mental bias and not of the logic of things. If he had first enquired
into the Wasp's habits, he would not have brought forward as a serious
argument an incident which had no connection with the important question
of animal reason.

I have reverted to this case to show the difficulties that beset the man
who confines himself to casual observations, however carefully carried
out. One should never rely upon a lucky chance, which may not occur
again. We must multiply our observations, check them one with the other;
we must create incidents, looking into preceding ones, finding out
succeeding ones and working out the relation between them all: then and
not till then, with extreme caution, are we entitled to express a few
views worthy of credence. Nowhere do I find data collected under such
conditions; for which reason, however much I might wish it, it is
impossible for me to bring the evidence of others in support of the few
conclusions which I myself have formed.

My Mason-bees, with their nests hanging on the walls of the arch which I
have mentioned, lent themselves to continuous experiment better than any
other Hymenopteron. I had them there, at my house, under my eyes, at
all hours of the day, as long as I wished. I was free to follow their
actions in full detail and to carry out successfully any experiment,
however long. Moreover, their numbers allowed me to repeat my attempts
until I was perfectly convinced. The Mason-bees, therefore, shall supply
me with the materials for this chapter also.

A few words, before I begin, about the works. The Mason-bee of the Sheds
utilizes, first of all, the old galleries of the clay nest, a part of
which she good-naturedly abandons to two Osmiae, her free tenants: the
Three-horned Osmia and Latreille's Osmia. These old corridors, which
save labour, are in great demand; but there are not many vacant, as the
more precocious Osmiae have already taken possession of most of them;
and therefore the building of new cells s