Cli. XII.] MELASTOM^l AXD THEIR AXIS. 



223 



This case is not like the last one, where the tree has 

 provided food and shelter for the ants, but rather one 

 where the ant has taken possession of the tree, and 

 brought with it the coccidce ; but I believe that its pre- 

 sence must be beneficial. I have cut into some dozens 

 of the cecropia trees, and never could find one that was 

 not tenanted by ants. I noticed three different species, 

 all, as far as I know, confined to the cecropice, and all 

 farming scale-insects. As in the bull's-horn thorn, there 

 is never more than one species of ant on the same tree. 



In some species of Melastomae there is a direct provi- 

 sion of houses for the ants. In each leaf, at the base of 



LEAF OF JIELASTOMA. 



the laminee, the petiole, or stalk, is furnished with a 

 couple of pouches, divided from each other by the mid- 

 rib, as shown in the figure. Into each of these pouches 

 there is an entrance from the lower side of the leaf. I 



