As the ants often travel some distance from their nest in search of food, they may certainly be said to be, in a limited sense, agents in the dispersal of seeds, for they not unfrequently drop seeds by the way, which they fail to find again, and also among the refuse matter which forms the kitchen midden in front of their entrances, a few sound seeds are often present, and these in many instances grow up and form a little colony of stranger plants. This presence of seedlings foreign to the wild ground in which the nest is usually placed, is quite a feature where there are old established colonies of _Atta barbara_, as is shown at Fig. A in Plate I., p. 21, where young plants of fumitory, chickweed, cranesbill, _Arabis Thaliana_, &c., may be seen on or near the rubbish heap. It would be interesting to make a list of all these ant-imported plants, and I think it quite likely that, if a sufficiently large number of nests were visited, some seedlings of cultivated species might be found amongst them, for we have seen that garden plants are frequently put under contribution. One can imagine cases in which the ants during the lapse of long periods of time might pass the seeds of plants from colony to colony, until after a journey of many stages, the descendants of the ant-borne seedlings might find themselves transported to places far removed from the original home of their immediate ancestors. It is a true cause, but at the same time it may be one which has, like many true causes, exceedingly small effects. One can scarcely look at the teeming population of an ant's nest, without asking whether there are any checks to their increase, and if so, what these checks are. I know very little of what foreign enemies they may have, though I have occasionally seen them captured by lizards, _Cicindela_ beetles, and spiders,[38] and it is well known that the females are eagerly sought for by birds at the season when they are above ground, and about to found new colonies; but I believe that ants are the ants' worst enemies, for fearful slaughter and mutilation often result from the encounter of armies of the same race, but belonging to different nests. [Footnote 38: I have seen the remains of ants at the bottom of the tube of trap-door spider nests, and watched a hunting spider, _Lycosa_, capture a large black ant (_Formica pubescens_), by entangling it in threads, which it deftly spun about its limbs, while running rapidly round the struggling victim in a circle, and dodging out of the way of the ant's mandibles. In England one may frequently see ants caught in the spiders' webs among the rose-bushes, and Mr. Blackwall says, in his Spiders of Great Britain and Ireland, that _Theridion riparium_ lives principally on ants.]