Page:Popular Science Monthly Volume 19.djvu/840

820 the ants prevent germination, is not invariably successful, but that a small percentage of stored seeds sometimes do begin to germinate. When this was the case, he also observed the highly interesting fact that the ants then knew the most effective method of checking further germination, for he found that in these cases they gnawed off the tip of the sprouting radicle. This fact deserves to be considered as one of the most remarkable among the many remarkable facts of ant psychology.

Passing on now to the harvesting ants of the New World, the insects here remove all the herbage above their nest in the form of a perfect circle, or "disk," fifteen to twenty feet in diameter. Every grass or weed within the disk is carefully felled, and, as the nests are situated in thickly-grown localities, the effect of the bald or shaven disk is highly conspicuous and peculiar, exactly resembling in miniature the "clearings" which are made by settlers in the backwoods. The disk, however, is not merely cleared of herbage, but also carefully leveled—all inequalities of the surface being reduced by pellets of soil being built into the hollows to an extent sufficient to make a uniformly flat surface. In the center of the disk is the gateway of the nest. From the disk in various directions there radiate out-roads or avenues, which are cleared and smoothed like the disk. These roads course through the thick grass, branching and narrowing as they go, till they eventually taper away. They are usually four to seven inches wide at their origin, and may be from sixty to three hundred feet in length. Along these roads there is always passing during the daytime a constant double stream of ants, one being laden and the other not.

In their manner of gathering and garnering grain these harvesters resemble in general the harvesters of Europe; but it is alleged by Dr. Lincecum that in one respect their habits manifest an astonishing, and indeed wellnigh incredible, advance upon those of their European allies. For this observer, who, it must be remembered, was the first to call attention to these ants in the New World, and whose other observations, extending over a number of years, have since been fully confirmed—this observer states in the most positive terms that the ants actually sow the seeds of a certain plant called the ant-rice, for the purpose of subsequently reaping a harvest of grain; hence these ants have been called the "agricultural ants." Now, there is no doubt, from the subsequent observations of McCook and others, that the ant-disks do very frequently support this peculiar kind of grass, and that the ants are particularly fond of its seed. Nevertheless, McCook did not himself witness the process of sowing, although he is not disposed to doubt the statements of his predecessor upon the subject. These statements, as already observed, are most emphatic and precise—Lincecum saying, in italics, that he knows and is certain about the fact; but until corroborated it is safest to regard the fact as not yet fully established.