98 ON THE HABITS OF ANTS. [lect. hi. 



(Carlina, Lamium) ; some have a number of glands 

 secreting a glutinous substance, over which the ants 

 cannot pass (Linncea, Gooseberry) ; in others the tube 

 of the flower is itself very narrow, or is almost closed 

 either by hairs or by internal ridges, which just leave 

 space for the proboscis of a bee, but no more. Lastly, 

 some, and especially pendulous flowers (Cyclamen, Snow- 

 drop), are so smooth and slippery that ants cannot 

 easily enter them, but often slip off in the attempt, 

 and thus are excluded ; just as the pendulous nests of 

 the weaver-birds preclude the entrance of snakes. 



