Dr. Büchner records the following instance on the authority of a friend (M. Theuerkauf) :— A maple tree standing on the ground of the manufacturer, Vollbaum, of Elbing (now of Dantzic) swarmed with aphides and ants. In order to check the mischief, the proprietor smeared about a foot width of the ground round the tree with tar. The first ants who wanted to cross naturally stuck fast. But what did the next? They turned back to the tree and carried down aphides, which they stuck down on the tar one after another until they had made a bridge, over which they could cross the tar-ring without danger. The above-named merchant, Vollbaum, is the guarantor of this story, which I received from his own mouth on the very spot whereat it occurred."1 In this case I confess I have my doubts as to the interpretation of the fact. Is it not possible that as the ants descended the tree, carrying the aphides, the latter naturally stuck to the tar, and would certainly be left there. In the same way I have seen hundreds of bits of earth deposited on the honey with which I fed my ants. 2 On one occasion Belt observed a community of leaf-cutting ants (Ecodoma), which was in the process of moving from one nest to another. Between the old burrows and the new one was a steep slope. Instead of descending this with their burdens, they cast 1 Mind in Animals, by Prof. Ludwig Büchner, p. 120. them down on the top of the slope, whence they rolled to the bottom, where another relay of labourers picked them up and carried them to the new burrow. It was amusing to watch the ants hurrying out with bundles of food, dropping them over the slope, and rushing back immediately for more.' With reference to these interesting statements, I tried the following experiment: Fig. 10. October 15 (see Fig. 10).-At a distance of 10 inches from the door of a nest of Lasius niger I fixed an upright ash wand 3 feet 6 inches high (a), and from the top of it I suspended a second, rather shorter wand (b). To the lower end of this d second wand, which hung just over the A • entrance to the nest (c), I fastened a flat glass cell (d) in which I placed a number of larvæ, and to them I put three or four specimens of L. niger. The drop from the glass cell to the upper part of the frame was only an inch; still, though the ants reached over and showed a great anxiety to take this short cut home, they none of them faced the leap, but all went round by the sticks, a distance of nearly 7 feet. At 6 P.M. there were over 550 larvæ in the glass cell, and I reduced its distance from the upper surface of the nest to about of an inch, so that the ants could even touch the glass with their antennæ, but could not reach up nor step down. Still, though the drop was so small, they all went round. At 11 P.M. the greater number of the larvæ had been carried off; so I put a fresh lot in the cell. The ants were busily at work. At 3 A.M. I visited them again. They were still carrying off the larvae, and all going round. At 6 A.M. the larvæ were all removed. I put a fresh lot, and up to 9 A.M. they went on as before. The following day (October 17) I took two longer sticks, each 6 feet 6 inches in length, and arranged them in a similar manner, only horizontally instead of vertically. I also placed fine earth under the glass supporting the larvæ. At 8 o'clock I placed an ant on the larvæ; she took one, and I then coaxed her home along the sticks. She deposited her larva and immediately came out again, not, however, going along the stick, but under the larvæ, vainly reaching up and endeavouring to reach the glass. At 8.30 I put her on the larvæ again, and as she evidently did not know her way home, but kept stretching herself down and trying to reach the earth under the glass cell, I again coaxed her home along the sticks. At 9.3 she came out again, and again went under the larvæ and wandered about there. At 10 I put her on the larvæ and again helped her home. At 10.15 she came out again, and this time went to the stick, but still wanted some guidance. At 10.45 she again reached the frame, but immediately came out again, and I once more coaxed her round. After wandering about some time with a larva in her jaws, she dropped down at 11.14. After depositing her larva, she came out directly and went R under the larvæ. I again coaxed her round, and this time also she dropped off the glass with her larva. At 12.30 she came out again, and for the last time I helped her round. After this she found her way by herself. At 12.20 another (No. 2) found her way round and returned at 12.37. For the next hour their times were as follows: Thus they both made 9 visits in an hour. As regards actual pace, I found they both did about 6 feet in a minute. Soon after these began, other ants came with them. It was a beautiful day, and all my ants were unusually active. At 1 P.M. I counted 10 on the sticks at once, by 1.30 over 30, and at 5 in the afternoon over 60. They went on working very hard, and forming a continuous stream till I went to bed at 11; and at 4 in the morning I found them still at work; but though they were very anxious and, especially at first, tried very hard to save themselves the trouble of going round, they did not think of jumping down, nor did they throw the larvæ over the edge. Moreover, as I had placed some sifted mould under the glass, a minute's labour would have been sufficient to heap up one or two particles, and thus make a little mound which would have enabled them to get up and down without going round. A mound inch high would have been sufficient; but it did not occur to them to form one. The following morning (October 18) I put out some larvæ again at 6 A.M. Some of the ants soon came; and the same scene continued till 11.30 A.M., when I left off observing. Again, on October 22, I placed a few larvæ in a glass, which I kept continually replenished, which was suspended of an inch above the surface of the frame containing their nest, but only connected with it by tapes five feet long. I then, at 6.30, put a L. niger to the larvæ; she took one and tried hard to reach down, but could not do so, and would not jump; so I |