I. A POST-CARD PICTURE OF A VILLAGE IN INDO-CHINA. THE BAMBOO PLAYS AN IMPORTANT PART IN THE INDUSTRY OF THE PEOPLE.

2. A POST-CARD PICTURE OF A SCENE IN THE TOWN OF VINH, ANAM, SHOWING THE TYPE OF HUTS AND THE BROAD HATS OF THE WOMEN.

ANT ACACIAS AND ACACIA ANTS OF MEXICO AND

CENTRAL AMERICA.

By W. E. SAFFORD.

[With 15 plates.]

Among the plants of the New World which have attracted the attention of early explorers and naturalists are certain acacias armed with large spines, which serve as nesting places for intrepid little stinging ants. These spines, which occur in pairs joined at the base, bear a resemblance to the horns of animals, some of them to the spreading or incurved horns of oxen or buffaloes, others to the erect horns of certain antelopes, while others, sometimes curiously twisted, suggest those of an ibex. From the base of each pair of spines at the median point grows a bipinnate lacy fernlike leaf, which at length falls off, leaving the branches and stems of the acacias studded with the persistent thorns. These leaves bear on their petiole or main stem one or more glands, which when young secrete nectar, often in such abundance that it drops to the ground; and on the tips of many of the leaflets small waxy bodies resembling microscopic eggs or pears, which abound in oil and protoplasm. On plate 2 is shown a leaf of Acacia cornigera from a plant growing in one of the greenhouses of the United States Department of Agriculture, bearing on its petiole an elongated nectar-gland and on its leaflets numerous apical bodies. Both the nectar secreted by the glands and the apical bodies on the leaflets furnish the ants with nutritious food and are fed by them to their larvæ cradled in the hollow thorns of the plant. When the bush is jarred or shaken the ants come swarming out furiously to attack the intruder with their stings. Certain writers hold the theory that these plants, commonly called bull-horn acacias, have been able to enlist the ants as a body guard, furnishing them quarters and subsistence, in return for their protection against leaf-cutting ants and other enemies, and the plants have accordingly been called myrmecophilous, or "antloving." Others refuse to accept this view, declaring that the

acacias "have no more need for their ants than dogs for their fleas." 1

The first writer to call attention to the remarkable relationship between the ants and the acacias was Francisco Hernandez, the distinguished protomedico of Philip II, sent by his sovereign in 1570 to study the resources of New Spain. In the Huasteca region of northeastern Mexico he came upon a thorny tree, called by the Aztecs Hoitzmamaxalli, or "Forked thorn," which he described under the Latin heading Arbor cornigera, " Horn-bearing tree," as follows:

The Hoitzmamaxalli is a tree with leaves resembling those of a mezquite or tamarind, yellow flowers, edible pods, and horns very like those of a bull, growing on the tree's trunk and branches. The leaves, which apparently we have no savor when tasted, are reputed to be an antidote for poisons. Pounded to a paste and applied to the bites of serpents and other venomous animals, the wounds beforehand having been scarified, they are said, within a space of six hours more or less, to counteract and extract all the venom, in the meantime assuming a black color. Moreover, within the horns there are generated certain slender ants, tawny-colored and blackish, whose sting is hurtful, causing pain which persists for a whole day. The eggs of these ants, wormlike in form, reduced to a powder and inserted into the ears, likewise distilling into them the juice of

FIG. 1.-Branch of Holtzmamaxalli. (Acacia hernandezii Safford) with "horns very much like

those of a bull." Figured by Hernandez from the leaves, allays earache; and a specimen growing in the Huaxteca region of the juice will also cure toothMexico (1576). ache. This plant grows in the warm region of the Huaxteca in localities near the Gulf coast both flat and hilly.2

On plate 3 is shown a pair of these hollowed hornlike spines, with the ants, larvae, pupae, and eggs which were taken from it.

The above description, written in Latin about the year 1575, but not published until after the death of Hernandez, was accompanied

1 See Wheeler, W. M. Observations on the Central American Acacia Ants, in Trans. Second Entomological Congress, pp. 110-139. 1912.

Hernandez, Francisco. Prodromus, p. 48. 1651.