INTERDEPENDENCE OF ORGANISMS 55 



Root aphids can usually be found in any corn field where 

 burrows 'of the little brown ant are common. There bur- 

 rows are easily seen after a rain, when the ants open them up 

 and toss out upon the surface annular mounds of little 

 pellets of earth. The aphids will be found by exposing 

 some of the com roots where they traverse lateral passage- 

 ways ramifying outward from the ants' nest. The ants will 

 usually promptly demonstrate their care-taking function in 

 the premises, by seizing any aphids that may be shaken off 

 from the roots and carrying them into their nests. An ac- 

 count of a cage that may be used for rearing such mixed 

 colonies in the laboratory will be foupd in the appendix. 



The record of this study may well consist of brief notes 

 on the things observed. 



