ANT ACACIAS AND ACACIA ANTS SAFFOKD. 385 



the leaves are young, secretes a honeylike liquid. Of this Ihe ants are very 

 fond ; and they are constantly running about from one gland to another to sip 

 up the honey as it is secreted. But this is not all; there is a still more wonder- 

 ful provision of more solid food. At the end of each of the small divisions 

 of the compound leaflets there is, when the leaf first unfolds, a little yellow 

 fruitlike body united by a point at its base to the end of the pinnule. Examined 

 through a microscope, this little appendage looks like a golden pear. When 

 the leaf first unfolds, the little pears are not quite ripe, and the ants are 

 continually employed going from one to another examining them. When an 

 ant finds one sufficiently advanced, it bites the small point of attachment; then 

 bending clown the fruitlike body it breaks it off and bears it away in triumph 

 to the nest. All the fruitlike bodies do not ripen at once, but successively, so 

 that the ants are kept about the young leaf for some time after it unfolds. 

 Thus the young leaf is always guarded by the ants; and no caterpillar or 

 larger animal could attempt to injure them without being attacked by the 

 little warriors. The fruitlike bodies are about one-twelfth of an inch long, and 

 are about one-third of the size of the ants ; so that the ant bearing one away 

 is as heavily laden as a man bearing a large bunch of plantains. I think 

 these facts show that the ants are really kept by the acacia as a standing army, 

 to protect its leaves from the attacks of herbivorous mammals and insects. 



The bull's-horn thorn does not grow at the mines in the forest, nor are 

 the small ants attending on them found there. They seem specially adapted 

 for the tree, and I have seen them nowhere else. * * * I sowed the seeds 

 of the acacia in my garden, and reared some young plants. Ants of many 

 kinds were numerous, but none of them took to the horns for shelter, nor the 

 glands and fruitlike bodies for food; for, as I have already mentioned, the 

 species that attend on the thorns are not found in the forest. The leaf-cutting 

 ants attacked the young plants and defoliated them ; but I have never seen 

 any of the trees out on the savannahs that are guarded by the Pfteudomyrma 

 touched by them, and have no doubt the acacia is protected from them by its 

 little warriors. The thorns, when they are first developed, are soft, and filled 

 with a sweetish, pulpy substance; so that the ant, when it makes an entrance 

 into them, finds its new house full of food. It hollows this out, leaving only 

 the hardened shell of the thorn. Strange to say, this treatment seems to 

 favor the development of the thorn, as it increases in size, bulging out towards 

 the base; whilst in my plants that were not touched by the ants, the thorns 

 turned yellow and dried up into dead but persistent prickles. I am not sure, 

 however, that this may not have been due to the habitat of the plant not 

 suiting it. 



These ants seem to lead the happiest of existences. Protected by their 

 stings, they fear no foe. Habitations full of food are provided for them to 

 commence housekeeping with; and cups of nectar and luscious fruits await 

 them every day. But there is a reverse to the picture. In the dry season 

 on the plains, the acacias cease to grow. No young leaves are produced, and 

 the old glands do not secrete honey. Then want and hunger overtake the ants 

 that have revelled in luxury all the wet season ; many of the thorns are de- 

 populated, and only a few ants live through the season of scarcity. As soon, 

 however, as the first rains set in, the trees throw out numerous vigorous 

 shoots, and the ants multiply again with astonishing rapidity. 



The plant described above by Belt was referred to Acacia sphaero- 

 cephala, but this is a Mexican species which does not grow in Nica- 

 ragua. The two bull-horns which do occur in the region of Belt's 



