hold on the ground; if it prevails, the Indian, or Mestizo, does not attempt to grow corn there again, as he knows the grass will spoil it, and he is too indolent to weed it out. Often, however, the brushwood has been cut down and burnt, and fresh crops of corn grown several times before the grass has gained such an advantage that the cultivator gives up the attempt to plant maize. There is then a struggle between the weedy shrubs and the grass. The leaf-cutting ants come to the aid of the latter. Grass they will not touch, excepting to clear it away from their paths. The thick forest they do not like, possibly because beneath its shade the ground is kept too damp for their fungus beds. But along the edge of the forest, by the sides of roads through it, that let in the air and sunshine, and in clearings, they abound. They are especially fond of the leaves of young trees, many of which are destroyed by them. Should the brushwood ultimately prevail, and cover the ground, the Indian or Mestizo comes again after a few years, cuts it down, and replants it with maize. But as most of his old clearings get covered with grass, he is continually encroaching on the edge of the forest, beating it back gradually, but surely, towards the north-east. As this process has probably been going on for thousands of years, I believe that the edge of the forest is several miles nearer the Atlantic than it was originally. In this way many acres in the neighbourhood of Pital were taken from the forest, and added to the grass-lands, whilst I was in the country. The brushwood-land does not yield such good crops as the virgin forest, but it is nearer to the huts of the cultivators, who live out on the savannahs, so that whenever the weedy shrubs gain possession of a spot sufficiently large for a clearing, and choke off the grass, these places are again cut down and burnt, and thus the forest is never allowed to establish outposts, or advanced stations, in the disputed ground. What would be the result if man were withdrawn from the scene, I do not know, but I believe that the forest would slowly, but surely, regain the ground that it has lost through long centuries. The thickets and dense brushwood that always spring up along the edge of the forest, and consist of many shrubs that the leaf-cutting ants do not touch, would gradually spread, and beat back the grass. In their shade and shelter, seeds from the forest would vegetate and grow, and thus, I think, very slowly, inch by inch, the forest would regain its long-lost territory, and gradually extend its limits towards the south-west, until it reached its old boundaries, where a change in the physical character of the land, or in the amount of moisture precipitated, would stay its further progress. It is far more likely, however, that man will drive back the forest to the very Atlantic than that he will quit the scene.