ri.] CHEVAUX DE FRISE. 37 



you touch an ant with a needle or a bristle, she is 

 almost sure to seize it in her jaws ; and if bees, when 

 visiting any particular species, were liable to have the 

 delicate tip of their proboscis seized on by the horny 

 jaws of an ant, we may be sure that such a plant 

 would soon be deserted. 



On the other hand, we know how fond ants are of 

 honey, and how zealously and unremittingly they 

 search for food. How is it, then, that they do not 

 anticipate the bees, and secure the honey for them- 

 selves ? Kerner has published a most interesting 

 memoir on this subject, and has pointed out a 

 number of ingenious contrivances by which flowers 

 protect themselves from the unwelcome visits of such 

 intruders. The most frequent are the interposition of 

 chevaux de frise, which, ants cannot penetrate, glutin- 

 ous surfaces which they cannot traverse, slippery 

 slopes which they cannot climb, or barriers which 

 close the way. 



Firstly, then, as regards chevaux defrise. In some 

 respects these are the most effectual protection, since 

 they exclude not only creeping insects, but also other 

 creatures, such as slugs. With this object, it will be 

 observed that the hairs which cover the stalks of so 

 many herbs usually point downwards. A good 

 example of this is afforded, for instance, by a plant, 

 Knautia dipsacifolia (Fig. 31), allied to our common 

 blue scabious. The heads of the common carline, 

 Carlina vulgaris (Fig. 33), again, present a sort of 

 thicket, which must offer an almost impenetrable 

 barrier to ants. Some species of plants are quite 

 smooth, excepting just below the flpwers. The 



