212 ENTOMOLOGY 



correlation with the food habits, as are also the various cephalic glands, 

 the chief functions of which are given as: (i) digestion, as the conversion 

 of cane sugar into grape sugar, and possibly starch into sugar; (2) the 

 chemical alteration of wax; (3) the production of special food substances, 

 which are highly important in larval development. 



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- 



''b 



FIG. 265. Acacia's ph(Brocephaia, an ant-piant. b, one of the "Belt's bodies"; g, gland; 

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

 der Botanik. 



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 

 a thorn (Fig. 265, 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 

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



