MUTUAL AID AND COMMUNAL LIFE AMONG ANIMALS 379 



ing account of the s^-mbiosis of the Aztec ants and the inibauba 

 tree: 



"In the forests of Soutli America jijrow the inibauba or so-called 

 candelabra trees, species of the genus Cecropia, which well deserve 

 their name, 'candelabra/ from the curious appearance given them 

 by the outsi)rin<!:ins bare branches, each Ijeariiip; a tuft of leaves at the 

 free end. These leaves are often attacked by the leaf-cutting ants of 

 the genus CEcodonia, which roam by 

 tens of thousands over the various 

 plants of the forest biting off the 

 leaves, that they may fall to the grountl, 

 where they are again seized, bitten into 

 pieces and the pieces carried into the 

 nests of the ants. In the nests they 

 serve as a medium on whicli grow cer- 

 tain molds or fun<i;i, nuich liked by the 

 ants. The candela])ra tree j^rotects it- 

 self from these leaf-robbing enemies by 

 an association with another ant species, 

 Aztcca instahilis, w^hich finds safe dwel- 

 ling places in the hollow trunk of the 

 tree and a special supply of food in a 

 brownish fluid secreted by it. Along 

 the tree trunk occur in regular order 

 little pits through which the female 

 Azteca can easily bore into the interior, 

 where she lays her eggs and establishes 

 colonies, so that soon the interior of 

 the whole trunk swarms with ants 



which rush out whenever the tree is shaken. But this alone would not 

 serve to protect the imbauba from the leaf cutters, for how could the 

 Aztecs dwellinc; inside the tree know of the j^resence of the lij;ht-f(K)ted 

 leaf -cutters without? But this is arranged for by the devel()j>ment on 

 the outside of the tree, at the very points where the thinner is greatest, 

 namely, on the jietioles of the younp;er leaves, of jKH-uliar little hairy 

 growths from which j)roject small white «!;rains which arc very nutri- 

 tious and not only easjerly eaten by ants, but i^arnercd by them to carry 

 into their nests, jjresumably as food for their larva*. Thus rij;ht where 

 protection is most needed the })l;int has develo])ed a .^tiwcial orphan 

 attractive to the fierce Aztec ants, so tiiat their constMut prescncx? at 



Fig. 233. — Piece of a branch of 

 the Inibauba tree, Cecropia, the 

 leaves cut away, showing at 

 the base of each petiole the 

 small tuft on the food; at the 

 rifiht some of this ant food en- 

 largeil. (After i;chim;)er.) 



