148 ROMANCE OF THE INSECT WORLD CHAP.- 



cemented into a kind of papier-mdcht with earth 

 and spiders' web. 



Curious Carpenter Ants (Pseudomyrma bicolor], 

 if so they may be termed, inhabit the strong 

 curved spines of the Bull's Horn Thorn, a 

 species of acacia, so called because the branches 

 and trunk are covered with spines, set in pairs, 

 which bear great resemblance to the horns of 

 that quadruped. When the thorns are first 

 developed, and are ready for tenancy, they are 

 soft and filled with a sweetish pulpy substance. It 

 the ants eat away, preserving the hollow hardened 

 shell, within which they live and rear their young. 

 Near the tip of the thorn an aperture is made for en- 

 trance and exit. Additional doorways are not required, 

 the partition separating the two thorns is burrowed 

 through, so that one opening serves for both (see 

 Fig. 23). The acacia does something more for the ants 

 than provide them with lodging and a stock of food 

 with which to commence to keep house. Its leaves 

 are bi-pinnate,* and at the base of each two leaflets 

 on the mid- rib a crater-like gland when the leaves are 

 young secretes a drop of a honey-like liquid of which 

 the ants are extremely fond, and they constantly run 

 from one luscious mass to the other, sipping greedily. 

 Nor is this all, the tree likewise provisions its guests 

 with solid food in the shape of yellow fruit-like 

 bodies, one at the end of each of the small divisions 

 of the compound leaflets. Examined through the 

 microscope they look like little golden pears. When 

 the leaf unfolds the fruits are not quite ripe, and the 

 ants are continually watching and investigating their 



