24 SPECIAL RELATIONS. [CHAP. 



some always by the mouth of the flower, others 

 always cutting a hole. He particularly mentions 

 that this was the case with bees of one and the 

 same species, and infers, therefore, that the different 

 individuals differ from one another in their degrees 

 of intelligence ; these observations, though of course 

 not conclusive, are interesting and suggestive. 



Lastly, some insects confine themselves to particu- 

 lar flowers. Thus, according to H. Miiller 



Andrena florea ^ .. Bryonia dioica 



Halictoides 

 Andrena hattorfiana 

 Cilissa melanura 

 Macropis labiata 

 Osmia adunca 



Species of Campanula, 

 Scabiosa arvensis. 

 Lythrum Salicaria. 

 Lysimachia vulgaris. 

 . Echium. 



The arrangements to which I have hitherto called 

 attention are for the most part of such a nature as to 

 adapt the flowers to the visits of insects. There are 

 others, however, of much interest which serve to pro- 

 tect them from unwelcome visitors, such as ants, 

 who would rob them of their honey without fulfilling 

 any useful purpose in return. Some plants are pro- 

 tected by downward pointing hairs, others by viscid 

 glandular hairs, others by the extreme smoothness of 

 their surface. In other cases the flower is closed by 

 barriers, which only leave sufficient space for the 

 slender proboscis of the bees, while others again, such 

 as the Foxglove, are closed boxes which bees only are 

 able to enter. 



Another remarkable peculiarity of plants, which 

 may I think possibly have reference to their rela- 



