MYRMECOPHILY, in its broadest sense, signifies a condition of friendship with ants, and includes the subject of the various insect and other guests kept or entertained in their nests by ants. The side of it to be considered now, however, is the relation of certain plants to ants, when this relation is, or is supposed to be, of mutual advantage. Such plants are termed myrmecophilous and are of great variety, especially in the tropics, That ants inhabit all sorts of cavities in trees and large vascular plants, such as cacti, is well known, and often they dig out the pithy interior or otherwise modify these cavities into homes fully adapted to their requirements. "The rigid vegetable tissues are an excellent protection against enemies," as Wheeler points out, "and the cavities are moist, dark and free from molds, so that they make perfect nurseries for the larva: and pupa:." It is a matter of com mon knowledge also that in most cases the plants thus utilized furnish a good deal of food material for the ants. The great mass•of ob servations bearing on this matter have been interpreted by many naturalists to support the view that many plants have developed as an adaptation through natural Selection elaborate structures to be used as ant-lodgings or even to furnish these insects with food-substances in order to attract certain pugnacious ants whose stings are formidable, because they will pro tect the plants from leaf-cutting ants or other leaf-destroying enemies. In this alleged
symbiotic arrangement the insects profit by the supply of special food-material growing on the plant and return the service by warding off harm; and it is said that mutual adaptations have occurred between the chosen kind of plant and the species of ant that inhabits its ap pointed cavities. The great body of facts col lected by Fritz Muller, Schimper, Belt, Semper, Beccari and others are accepted, and some of their interpretations are admitted, but recent students of the matter regard the theory as far overstrained and doubt that true symbiosis can be shown to exist in any case. The latest and fullest treatment of the matter will be found in William M. Wheeler's 'Ants' (New York 1910).