96 ON THE HABITS OF ANTS. [LECT. in. 



So far as I know, however, there are no plants which 

 are specially modified, in order to be fertilised by 

 ants ; and, indeed, even to those small flowers which 

 any little insect might fertilise, the visits of winged 

 insects are much more advantageous ; because, as Mr. 

 Darwin has shown in his excellent work on cross - 

 and self-fertilisation of plants, it is important that 

 the pollen should be brought, not only from a different 

 flower, but also from a different plant, while creeping , 

 insects, such as ants, would naturally pass from flow&MJ 

 to flower of the same plant. 



Under these circumstances, it is important to plants 

 that ants should not obtain access to the flowers, 

 which they would otherwise rob of their honey, with- 

 out conferring on them any compensating advantage. 

 Accordingly, we not only find in flowers various modes 

 of attracting bees, but also of excluding ants ; and 

 in this way ants have exercised more influence on 

 the vegetable kingdom than might be supposed. Some- 

 times, for instance, flowers are protected by chevaux 

 de frise of spines and fine hairs pointing downwards 

 (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. 



