THE PLANT AS A HOST 37 



number, however, survive to carry on the race 

 during the time of scarceness. 



Recent investigation has shown that the story 

 of this strange compact between the ant and 

 the Acacia trees is not at all exaggerated. The 

 same state of affairs has been observed in quite 

 a number of trees. In the case of the hollow- 

 stemmed Cecropias, it has been found that the 

 specimens which had suffered from the attacks of 

 leaf-cutting ants were for some reason or other 

 without their bodyguard. With the Cecropias the 

 ants enter the stems by means of a little door 

 which they always make at one spot on the stem 

 where the tissue is very thin. Here also the plants 

 are provided with a plenteous supply of food. 

 Near the base of the leaf-stalks are to be found 

 brown patches on which are collections of oval 

 bodies. These are highly nutritious, and are 

 eaten greedily by the ants. It is certainly signi- 

 ficant that, both in the case of the Cecropias and 

 the Acacias, the food bodies are absent where the 

 particular species is not inhabited by ants. 



It must not be supposed that in all cases 

 where ants and other small creatures are found 

 to be associated with plants it is possible to make 

 out a clear case of mutual help. The curious 

 plant Myrmecodia tuberosa, from the Malay Archi- 



