whatever the quality of its
surface, will sometimes suit them and sometimes not? Do they judge
their new lodging by sight? But then no mistake would be possible; the
sense of sight would tell them at the outset whether the object within
reach was suitable or not; and emigration would or would not take
place according to its decision. And then how can we suppose that,
buried in the dense thicket of a pellet of cotton-wool or in the
fleece of an Anthophora, the imperceptible larva can recognize, by
sight, the enormous mass which it is perambulating?

Is it by touch, by some sensation due to the inner vibrations of
living flesh? Not so, for the Meloes remain motionless on insect
corpses that have dried up completely, on dead Anthophorae taken from
cells at least a year old. I have seen them keep absolutely quiet on
fragments of an Anthophora on a thorax long since nibbled and emptied
by the Mites. By what sense then can they distinguish the thorax of an
Anthophora from a velvety pellet, when sight and touch are out of the
question? The sense of smell remains. But in that case what exquisite
subtlety must we not take for granted? Moreover, what similarity of
smell can we admit between all the insects which, dead or alive, whole
or in pieces, fresh or dried, suit the Meloes, while anything else
does not suit them? A wretched louse, a living speck, leaves us
mightily perplexed as to the sensibility which directs it. Here is yet
one more riddle added to all the others.

After the observations which I have described, it remained for me to
search the earthen surface inhabited by the Anthophorae: I should then
have followed the Meloe-larva in its transformations. It was certainly
_cicatricosus_ whose larvae I had been studying; it was certainly this
insect which ravaged the cells of the Mason-bee, for I found it dead
in the old galleries which it had been unable to leave. This
opportunity, which did not occur again, promised me an ample harvest.
I had to give it all up. My Thursday was drawing to a close; I had to
return to Avignon, to resume my lessons on the electrophorus and the
Toricellian tube. O happy Thursdays! What glorious opportunities I
lost because you were too short!

We will go back a year to continue this history. I collected, under
far less favourable conditions, it is true, enough notes to map out
the biography of the tiny creature which we have just seen migrating
from the camomile-flowers to the Anthophora'