parallel with each other, which not only serve to retain the leaf in its spiral form, but also serve the caterpillar as a kind of ladder, by which it mounts, and on which it rests while cutting out fresh portions of leaf. [Illustration: LEAF-NEST UNWOUND. ] It sometimes happens accidentally to this caterpillar that the case becomes detached from the leaf, or naturalists have purposely severed a portion to see what would be the result; but this does not greatly disturb the insect, for as long as a single thread of silk remains to hold the pieces together, the caterpillar is able to repair the evil. It will unite the fractured portion almost imperceptibly by means of silken threads, and proceed with its case as before; but if the leaf dry up and wither, the insect is then compelled to desert it, and to select a younger and fresher leaf for its operations. What is still more curious, on the completion of the dwelling, the caterpillar sometimes wishes to make an excursion to another part of the leaf, and to take its house with it, and this it accomplishes in the following manner. Coming more than three parts out of the cone, the creature makes new skeins in advance of the old, and attempts to pull the cone forward by their means; but finding that this does not succeed, it bends its body back, and quickly severs the old threads and the portion of leaf which keeps the case immovable. It is now able to draw the case onwards a certain distance, after which it has only to repeat the operation, and make other new skeins in advance of these, to continue its onward journey. Thus it arrives at the opposite edge of the leaf, where it carefully adjusts its case to the under side, fastening it with great ingenuity, and drawing the threads tighter where the cone is not properly balanced. In all these cases, silk is the useful material by which the caterpillar secures its nest, and provides for its own safety: it is also a constant resource in case of danger, or of accident, as the following anecdote will show. A caterpillar of the goat-moth, being confined in a smooth glass sugar-basin, managed to crawl up the slippery sides and escape. This excited great surprise in the naturalist (Rösel) who had imprisoned the creature, and he therefore took occasion closely to watch its proceedings when again placed in a similar vessel. It was with surprise and admiration that he now saw the caterpillar constructing a silken ladder on the side of the glass; the natural gum of the silk being sufficient to secure it even to that perfectly smooth surface. Up this ladder the creature crawled, and thus easily and expeditiously made its escape. [Illustration: SILKEN LADDER SPUN BY THE GOAT-MOTH CATERPILLAR. ]