230 



ENTOMOLOGY 



Numerous special sensory adaptations also occur. In fact, the 

 whole organization of the honey bee has become profoundly modified 

 in relation to nectar and pollen. Many other insects have the same 

 food but none of them sustain such intimate relations to the flowers as 

 do the bees. 



Ant-plants. There are several kinds of tropical plants which are 

 admirably suited to the ants that inhabit them. Indeed, it is often as- 

 serted that these plants have become modified with special reference to 

 their use by ants, though this is a gratuitous and improbable assumption. 



Belt found several species of Acacia in Nicaragua and the Amazon 

 valley which have large hollow stipular thorns, inhabited by ants of the 

 genus Pseudomyrma. The ants enter by boring a hole near the apex of 



PIG. 268. Acacia sphcerocephala, an ant-plant, b, one of the "Belt's bodies"; g, gland; 

 s, s, hollow stipular thorns, perforated by ants. Reduced. From Strasburger's Lehrbuch 

 der Botanik. 



a^ thorn (Fig. 268, s). The plant affords the ants food as well as shelter, 

 for glands (g) at the bases of the petioles secrete a sugary fluid, while 

 many of the leaflets are tipped with small egg-shaped or pear-shaped 

 appendages (b) known as "Belt's bodies," which are rich in albumin, 

 fall off easily at a touch, and are eaten by the ants. These ants drive 

 away the leaf-cutting species, incidentally protecting the tree in which 

 they live. 



The ant- trees (Cecropia adenopus) of Brazil and Central America 

 havfc often been referred to by travelers. When one of these trees is 

 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. '2 69, 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 



