These reiterated borings are not at all rare: I noted a score of them on my tiles; and, in the case of some cells, the operation was repeated before my eyes as often as four times. Nothing tells us that this number was not exceeded in my absence. The little that I observed prevents me from fixing any limit. And now a momentous question arises: is the egg really laid each time that the probe enters a cell? I can see not the slightest excuse for supposing the contrary. The ovipositor, because of its horny nature, can have but a very dull sense of touch. The insect is apprised of the contents of the cell only by the end of that long horse-hair, a not very trustworthy witness, I should imagine. The absence of resistance tells it that it has reached an empty space; and this is probably the only information that the insensible implement can supply. The drill boring through the rock cannot tell the miner anything about the contents of the cavern which it has entered; and the case must be the same with the rigid filament of the Leucopses. Now that the thread has reached its goal, what does the cell contain? Mildewed honey, dust and rubbish, a shrivelled larva, or a larva in good condition? Above all, does it already contain an egg? This last question calls for a definite answer, but as a matter of fact it is impossible for the insect to learn anything from a horse-hair on that most delicate matter, the presence or absence of an egg, a mere atom of a thing, in that vast apartment. Even admitting some sense of touch at the end of the drill, one insuperable difficulty would always remain: that of finding the exact spot where the tiny speck lies in those spacious and mysterious regions. I go so far as to believe that the ovipositor tells the insect nothing, or at any rate very little, of the inside of the cell, whether propitious or not to the development of the germ. Perhaps each thrust of the instrument, provided that it meets with no resistance from solid matter, lays the egg, to whose lot there falls at one time good, wholesome food, at another mere refuse.