We will leave them to their grazing, with which they seem quite satisfied, and ask ourselves a certain question relating to cleanliness. How does the little Psyche get rid of his digestive refuse? Remember that he is enclosed in a sack. One dare not entertain the thought of ordure ejected and accumulating at the far end of the dazzling white plush cap. Filth cannot dwell under so elegant a covering. How is the sordid evacuation managed? Despite the fact that it ends in a conical point, in which the lens reveals no break of continuity, the sack is not closed at the hinder end. Its method of manufacture, by means of a waistband whose fore-edge increases in dimensions in proportion as the rear-edge is pushed farther back, proves this sufficiently. The hinder end becomes pointed simply owing to the shrinking of the material, which contracts of itself at the part where the caterpillar’s decreasing diameter no longer distends it. There is thus at the point a permanent hole whose lips remain closed. The caterpillar has only to go a little way back and the stuff expands, the hole widens, the road is open and the excretions fall to the ground. On the other hand, so soon as the caterpillar takes a step forward into his case, the rubbish-shoot closes of itself. It is a very simple and very ingenious mechanism, as good as anything contrived by our seamstresses to cope with the shortcomings of a boy’s first pair of breeches. Meanwhile the grub grows and its tunic continues to fit it, is neither too large nor too small, but just the right size. How is this done? If the text-books were to be credited, I might expect to see the caterpillar split his sheath lengthwise when it became too tight and afterwards enlarge it by means of a piece woven between the edges of the rent. That is what our tailors do; but it is not the Psyches’ method at all. They know something much better. They keep on working at their coat, which is old at the back, new in front and always a perfect fit for the growing body. Nothing is easier than to watch the daily progress in size. A few caterpillars have just made themselves a hood of sorghum-pith. The work is perfectly beautiful; it might have been woven out of snow-flakes. I isolate these smartly-dressed ones and give them as weaving-materials some brown scales chosen from the softest parts that I can find in old bark. Between morning and evening, the hood assumes a new appearance: the tip of the cone is still a spotless white, but all the front part is coarse drapery, very different in colouring from the original plush. Next day, the sorghum felt has wholly disappeared and is replaced, from one end of the cone to the other, by a frieze of bark.