BIOLOGIC RELATIONS BETWEEN PLANTS AND ANTS. 413 



indirect services. Its essential parts are a double, paired gland and a 

 single unpaired gland, there being secreted by one of these, as is prob- 

 ably the case with all the hymenoptera, an acid liquid, while the secre- 

 tion of the other is alkaline. From the admixture of these is formed a 

 true acid venom whose irritating property is partly due to the pres- 

 ence of formic acid. This venom is discharged into an inoculating 

 apparatus developed in a greater or less degree in different species. 

 The pain produced by the bite of indigenous species of ants is but slight, 

 but exotic species may cause suffering of considerable intensity and 

 duration. 



This rapid review of the external organization of ants will enable us 

 to account for various relations that exist between them and the vege- 

 table world. 



The first relations between ants and vegetables have undoubtedly 

 been those of the eaters and the eaten. There are in fact quite a num- 

 ber of species of ants that obtain their food from living vegetables. Of 

 these the most celebrated, and justly so, are the harvester ants. Their 

 habits were known in the most ancient times. "The ant," says Solo- 

 mon (Prov. vi, 8), "provideth her meat in the summer and gathereth 

 her food in the harvest." Aelian, an author of the third century of our 

 era, not only notes their gathering of seeds, but describes the means 

 employed by them to keep their grains from dampness and their way 

 .of preventing germination by boring through the germ outside of the 

 seed. An Arabic book of the seventh century says, in speaking of ants: 

 "They store up wheat for food and dry it in the sun. If they fear that 

 the grain may germinate they take away its ball, cutting it in two 

 fragments. If we reflect we will be conviuced that the ant is an intel- 

 ligent insect." Montaigne, who lived in the south of France and had 

 traveled in Italy, was acquainted with the habits of the harvester ants, 

 which he describes with great precision. "They spread," says he, "in 

 the open air their grains and seeds to aerate, freshen and dry them, when 

 they see that they are getting moist and smelling moldy, for fear that 

 they may become corrupt and rotten. But the caution and foresight 

 that they use in dealing with barley grains surpasses all that human 

 prudence could imagine. For fear lest the grain sprout and lose its 

 qualities and properties as a store of food, they gnaw the end of it 

 where the germ is wont to appear." 



These data, collected by the old authors, have, however, been contro- 

 verted by recent authorities — Swainmerdam, Buffon, Latreille, and, 

 above all, P. Huber, the great observer of ants — and it was not until 

 recently that Lespes and Moggridge clearly proved the industrious 

 habits of the harvester ants. 



The two principal species of harvester ants, Aphoenogaster (Atta) 

 structor and A. barbara, are rare in the north, quite common in central 

 Europe, and abundant on the shores of the Mediterranean. The work- 

 ers are remarkable lor their differences in height and appearance. They 



