1^^^] Gee: Behavior of Leeches 249 



he considers as evidence of association formation in the earth- 

 worm. This would lead one to conjecture that the same capacity 

 is present in the leeches experimented upon in connection with 

 the present work. No experiments have been conducted to deter- 

 mine whether the leeches Glossiphonia stagnalis and Dina micro- 

 stoma are capable of forming simple types of associations. It is 

 not at all improbable that such is the case, but I see no difficulty 

 in accounting for any of the features of their behavior on the 

 basis of the simpler characteristics common to the behavior of 

 the lower organisms. 



