INSECTS IN RELATION TO PLANTS 



213 



handled roughly, hosts of ants rush out from small openings in the stems 

 and pugnaciously attack the disturber. Just above the insertion of 

 each leaf is a small pit (Fig. 266, a, b) where the wall is so thin as to form 

 a mere diaphragm, through which an ant (probably a fertilized female) 

 bores and reaches a hollow internode. To establish communication be- 

 tween the internodal chambers, the ants bore through the intervening 

 septa (Fig. 267) . They seldom leave the Cecropia plant, unless disturbed, 

 and even keep herds of aphids in their abode. The base of each petiole 



FIG. 266. Portion of young stem of Cecropia adenopus, 



showing internodal pits, a and b. Natural size. 

 Figures 266-268 are from Schimper's Pflanzengeo graphic. 



FIG. 267. Cecropia adenopus. 

 Portion of a stem, split so as to show 

 internodal chambers and the inter- 

 vening septa perforated by ants. 



bears (Fig. 268) tender little egg-like bodies ("Miiller's bodies") which 

 the ants detach, store away and eat; the presence of these bodies is a 

 sure sign that the tree is uninhabited by these ants, which, by the way, 

 belong to the genus Azteca. 



It is too much to assert that the ants protect the Cecropia plant in 

 return for the food and shelter which they obtain. All ants are hostile 

 to all other species of ants, with few exceptions, and even to other col- 

 onies of their own species; so that their assaults upon leaf-cutting ants 

 are by no means special and adaptive in their nature, and any protec- 



