RELATIONS OF ANTS TO VASCULAR PLANTS. 



37 



is still young (50 cm. to 2 m. high) at a particular point, a small 

 depression at the upper end of a furrow at the top of the internode, 

 where, as Schimper has shown, the wall lacks the fibro-vascular bun- 

 dles and is most easily perforated. Von Ihering calls the depression 

 the " prostoma," the perforation which is formed in it the "stoma." 

 The queen thus enters an internode by making a stoma and feeds on 

 the tissue ( " stomatome ") which, according to von Ihering, soon pro- 

 liferates over and closes the opening from the inside. In the small 

 internodal cavity the first workers, six to eight in number, are reared, 

 and these restore communication with the outside world by again open- 

 ing the stoma. Von Ihering 

 says that as many as five to ten 

 queens may each start a colony 

 in one of the internodes of the 

 same tree, that these colonies 

 forsake the internodes in which 

 they were reared and migrate 

 to more distal internodes and 

 that they eventually engage 

 with one another in conflicts 

 that terminate in the death of 

 all except one of the queens 

 and a fusion of the worker 

 personnel of the different colo- 

 nies to form one larger com- 

 munity. Such a fusion of 

 hostile colonies is so contrary 

 to what is known to occur in 

 other ants that it may well be 

 doubted. It is more probable 

 that only one of the original 



colonies together with its queen lapa, Mexico. (Original.) The entrances 



survives and that all the others are near the tips of the thorns - 

 are either massacred, or driven away from the tree. 



After this single colony has grown and perforated the septa it starts 

 a spindle-shaped carton nest in the bole, a little distance above the 

 ground. This so-called "metropolitan" nest (Fig. 174), which was 

 discovered by von Ihering, resembles the carton nests built by other 

 species of the genus on the branches of Cccropia and other trees. 

 Where the nest occurs the bole of the Cecropia presents a spindle- 

 shaped enlargement, which von Ihering regards as a gall" the largest 

 known gall," but his figures and several of these nests recently acquired 



FIG. 177. Hollow thorns of Acacia sp. 

 nhabited by Pseudomyrmax fiilvesceus ; Ja- 



