104 THE PLANT WORLD 



both rooms of their house. Once established in their new quarters they 

 raise their young and make it their home. 



It is obviously of great importance to the plant to have its little 

 warriors always on guard, and this is accomplished by so completely 

 supplying them with attractive food and drink that they have no desire 

 to leave the plant. On each leafstalk, a little way from the base, there 

 is a good sized gland that secretes abundantly a sweet liquid which the 

 ants delight in. One or more ants are almost always to be seen near a 

 gland, either sucking the nectar or waiting for more to appear. But of 

 course they can not live on all sweets any more than we can, and some 

 solid, nutritious food is necessary. This the plant provides in the form 

 of pear-shaped food bodies, which are produced at the extremities of 

 certain leaflets, in such a position that to get at them the ants must 

 travel over a considerable portion of the leaf. The food-bodies ripen a 

 few at a time, and thus keep the ants traveling over the leaf, day after 

 day, for some little while. When ready to pick they are of a rich golden 

 color, and filled with material like the meat of a nut. Upon finding one 

 in this condition, an ant bites through its slender point of attachment 

 and bears it in triumph to the nest. 



The acacia just described has in some respects the most perfect 

 provision for keeping a body-guard of any known plant, but there are 

 others in which very efficient though different means of keeping an ant- 

 garrison have been observed. This is true of the "imbauba" or 

 trumpet-tree of tropical America, which lodges colonies of ants in its 

 hollow stem. Their entrance is made easy by thin places in the stem- 

 wall, through which they can easily bore, and once inside, they cut a 

 small hole through the thin partitions which extend across the stem -cavity 

 at the joints and thus get the run of the whole interior. The chambers 

 into which the partitions divide their dwelling are used for different 

 purposes. One is the queen's apartment ; in some, grubs of different 

 ages are kept ; while in others are confined numerous small ' ' scale- 

 insects," somewhat like plant-lice. These suck the juices of the plant 

 and exude from the back a sweet liquid of which the ants are very fond. 

 These scale insects are tended with great care and have been aptly 

 compared to cows in their relations to the colony. They render 

 unnecessary any secretion of nectar by the plant, and we find only food- 

 bodies. These are produced as outgrowths from a rather large cushion 

 situated on the leafstalks near the base, and while they resemble the food 

 bodies of the bull's-horn acacia in form and nutritious contents, the 

 crop from a single leaf is not so soon exhausted, and as long as the leaf 

 is vigorous the ants find every day fresh tid-bits awaiting them on the 

 same cushion. This keeps the ants traveling back and forth over the 

 plant a good deal. If a leaf be touched they immediately assume the 



