Considerable intelligence is shown by worms in their manner of plugging up their burrows. If man had to plug up a cylindrical hole with such objects as leaves, petioles or twigs, he would push them in by their pointed ends, but if these were thin relatively to the size of the hole, he would probably insert some by their broader ends. Intelligence would certainly be his guide in such a case. But how worms would drag leaves into their burrows, whether by their tips, bases, or middle parts, has been a matter of interest to many. Darwin, who experimented upon the subject, found it especially desirable to experiment with plants not native to his country, for he conceived that although the habit of dragging leaves into their burrows is undoubtedly instinctive with worms, yet instinct could not teach them how to act in the case of leaves about which their progenitors knew nothing. Did they act solely through instinct, or an unvarying inherited impulse, they would draw all kinds of leaves into their burrows in the same manner. Having no such definite instinct, chance might be expected to determine whether the tip, base, or middle might be seized. If the worm in each case first tries many different methods, and follows that alone which proves possible or the most easy, then both instinct and chance are ruled out of the solution of the question. But to act in this manner, and to try different methods, makes what in man would be called intelligent action. Three species of pine-leaves are mentioned by Darwin as being regularly drawn into the mouths of worm-burrows on the gravel-walk in his garden. These leaves consist of two needles, which are united to a common base, and it is by this point that they are almost invariably drawn into the burrows. As the sharply-pointed needles diverge somewhat, and as several are drawn into the same burrow, each tuft forms a perfect _chevaux-de-frise_. Many tufts were pulled up in the evening, but by the ensuing morning fresh leaves had taken their places, and the burrows again well protected. Impossible it would be to drag these leaves to any depth into the burrows, except by their bases, as a worm cannot seize hold of the two leaves at the same time, and if one alone were seized by the apex, the other would be pressed against the ground and resist the entry of the one that was seized. That the worms should do their work well, it was very essential that they drag the pine-leaves into their burrows by their bases, that is, where the two needles are conjoined. But how they are guided in this work was at first perplexing. The difficulty, however, was soon settled. With the assistance of his son Francis, the elder Darwin set to work to observe worms in confinement during several nights by the aid of a dim light, while they dragged the leaves of the aforementioned kinds into their burrows. They were seen to move the anterior extremities of their bodies about the leaves, and on several occasions when they touched