This trunk, of which the butterfly makes such good use, is composed of two filaments more or less long, horny, concave in their interior surfaces, and fastened together by their edges. When cut transversely, one sees, according to Réaumur,[47] that the interior is composed of three small rings. Consequently, there are three canals in the trunk: one central, the other two lateral (Fig. 138). Are all these three used to conduct the juice of flowers into the butterfly's body? Réaumur has made some very interesting observations on this subject, by observing a moth which was sucking a lump of sugar whilst its portrait was being taken. [47] Planche 9, Fig. 10, 5e Mémoire, "Sur les parties extérieures des papillons." [Illustration: Fig. 138.--Section of a Butterfly's Trunk, after Réaumur.] "I held in one hand," says Réaumur, "a powerful magnifying glass, which I brought near to that part of the trunk I wished to examine; I was sometimes half a minute, or nearly a minute, without perceiving anything, after which I saw clearly a little column of liquid mounting quickly along the whole length of the trunk. Often this column appeared to be intersected by little balls, which seemed to be globules of air which had been drawn up with the liquid. "This liquid ascended thus during three or four seconds, and then ceased. At the end of an interval of a greater number of seconds, or sometimes after an interval as short, I saw some fresh liquid mounting up along the trunk. But it was straight up the middle of the trunk that it seemed to ascend. "The Author of Nature has given to insects means of working, which, though very simple, we cannot divine, and which often we are not able even to perceive. Whilst I was observing the trunk of our butterfly, between the columns of liquid which I saw ascending, there were, but more rarely, times when I saw, on the contrary, liquid descending from the base of the trunk to the point. The descending liquid occupied half or two-thirds of the tube. It was no longer difficult to perceive how the butterfly is able to nourish itself on honey, the thickest syrup, and even the most solid sugar. The fluid it sends down is probably very liquid; it drives against the sugar, moistens, and dissolves it. The butterfly pumps this liquid up again when it is charged with sugar, and conducts it along as far as the base of its trunk, and beyond it." The life of the perfect insect is generally very short. Like nearly all other insects, they die as soon as they have propagated their species. The female lays her eggs, which vary in shape, on the plant which is to nourish her progeny. The colour is also very various, and passes through all sorts of shades. At the moment they are laid, many are covered with a gummy substance, insoluble in water, which serves to stick them on the plant.