302 



.INTS. 



selves break down to form the secretion, differ from the salivary 

 glands which secrete a liquid without undergoing disintegration. 



5. Pith and Other Vegetable Tissues. Dahl ( 1901 ) describes cer- 

 tain ants of the Uismarck archipelago and their larvae as feeding on 



FIG. 172. Cecropia adenopus (Schimper.) A, Tip of branch with leaves cut off; 

 t, trichilia at base of leaf petioles ; x . prostoma or depression in internode ; .r'. stoina 

 or opening to hollow internode made by Azteca muelleri at the prostoma. B, Lon- 

 gitudinal section of stem showing the hollow internodes and at (.v) the septa per- 

 forated by the ants. 



the pith in the twigs of Clerodendron, and von Ihering (1907) finds 

 that Azteca muelleri eats the tissue that grows over the perforation 

 through which it enters the hollow twigs of the Cecropia. There is, 

 of course, no myrmecophilous adaptation on the part of the plants in 

 these cases. 



Turning now to the ants which are supposed to take advantage of 

 the inducements offered by the plants, we find in both hemispheres 

 many species that are very fond of wandering over the vegetation and 

 visiting the nectaries, food-bodies, etc. In the tropics whole genera 

 have become largely or exclusively arboreal, but this does not mean 



