Both in Brazil and in Nicaragua I paid much attention to the relation between the presence of honey-secreting glands on plants, and the protection the latter secured by the attendance of ants attracted by the honey. I found many plants so protected; the glands being specially developed on the young leaves, and on the sepals of the flowers. Besides the bull's-horn acacias, I, however, only met with two other genera of plants that furnished the ants with houses, namely, the trumpet tree and some of the evergreen shrubs; but I have no doubt that there are many others. The stem of the Cecropia, or trumpet tree, is hollow, and divided into cells by partitions that extend across the interior of the hollow trunk. The ants gain access by making a hole from the outside, and then burrow through the partitions, thus getting the run of the whole stem. They do not obtain their food directly from the tree, but keep brown scale insects in the cells, which suck the juices from the tree, and secrete a honey-like fluid that exudes from a pore on the back, and is lapped up by the ants. In one cell eggs will be found, in another grubs, and in a third pupae, all lying loosely. In another cell, by itself, a queen ant will be found, surrounded by walls made of a brown waxy-looking substance, along with about a dozen scale insects to supply her with food. I suppose the eggs are removed as soon as laid, for I never found any along with the queen ant. If the tree be shaken, the ants rush out in myriads, and search about for the molester. This case is not like the last one, where the tree has provided food and shelter for the ants, but rather one where the ant has taken possession of the tree, and brought with it the scale insects; but I believe that its presence must be beneficial. I have cut into some dozens of the trumpet trees, and never could find one that was not tenanted by ants. I noticed three different species, all, as far as I know, confined to the trumpet tree, and all farming scale insects. As in the bull's-horn thorn, there is never more than one species of ant on the same tree.