and bees in their struggle for existence. The ants neither restrict their diet, like the termites, to comparatively innutritious substances such as cellulose, nor like the bees to a very few substances like the honey and pollen of the evanescent flowers, nor do theyr build elaborate combs of expensive materials, such as wax. Even paper as building material has been very generally outgrown and abandoned by the ants. Waxen and paper cells are not easily altered or repaired, and insects that are wedded to this kind of architecture, not only have to expend much time and energy in collecting and working up their building materials, but they are unable to move themselves or their brood to other localities when the nest is disturbed, when the moisture or temperature become unfavorable or the food supply fails. The custom of depending on a single fertilized queen as the only reproductive center or organ of the colony has also been outgrown by many ants. At least the more dominant and successful species have learned to cherish a number of these fertile individuals in the colony. Finally, the manifold and plastic relationships of ants to plants and other animals are in marked contrast with the circumscribed and highly specialized ethological relationships of the social bees and wasps. The termites undoubtedly resemble the ants most closely in plasticity, but the careful studies of Grassi and Sandias, Sjöstedt, Froggatt, Silvestri, Heath and others, have shown that these insects, too, are high specialized, or one-sided in their development. This is best seen in their extreme sensitiveness to light, for this practically confine them to a subterranean existence and excludes them from many of the influences afforded by a more varied and illuminated environment.
There can be little doubt that the ants have become dominant through their exquisitely terrestrial habits, a fact which Espinas (1877) was, I believe, one of the first to notice. He says: "Ants owe their superiority to their terrestrial life. This assertion may seen paradoxical, but consider the exceptional advantages afforded by a terrestrial medium to the development of their intellectual faculties, compared with an aërial medium! In their air there are the long flights without obstacles, the vertiginous journeys far from real bodies, the instability, the wandering abount, the endless forgetfullness of things and oneself. On the earth, on the contrary, there is not a movement that is not a contact and does not yield precise information, not a journey that fails to leave some reminiscence; and as these journeys are determinate, it is inevitable that a portion of the ground incessantly traversed should be registered, together with its resources and its dangers, in the animal's imagination. Thus there results a closer and much more direct communication with the external world. To employ matter, moreover, is
