30 PLANT LIFE. 



tips are very marked in certain Dandelions and in 

 the Hawkweed of the Alps, where, probably, they are 

 most required and are not at all conspicuous in the 

 Lowland forms. 



Very often one may distinguish at the base of the 

 sepals of the Campion (^Lychnis diurna), a neat round 

 hole ; this is the work of the humble bee, which steals 

 honey by biting this opening in preference to doing its 

 duty by entering the tube in the proper way. It may 

 be that this explains the very peculiar sepals of the 

 Bladder Campion which bulge out to form a sort of 

 bladder. It would be almost impossible for the humble 

 bee to bore a hole in the right direction in this species. 



A very interesting figure is given by Kerner in which 

 certain ants are shown in ferocious attitudes on the 

 head of a thistle, protecting the flower against a cock- 

 chafer, which insect is a vegetable demon of the most 

 destructive kind. It is said that the honey glands 

 found on the stipules of the Common Vetch ( Vicia 

 septum) attract these ant-guards, but it is not easy to 

 prove the fact by observation. 



With a little careful observation, it is easy in almost 

 any example that may be available to get a clearer 

 idea of the meaning of most of the details of the 

 structure of a flower, by taking into consideration the 

 three necessities mentioned above : — (a) pollination by 

 insects, snails, wind, or water; (b) protection against 

 weather ; and (c) protection against unnecessary or 

 destructive insects. Engineering necessities for the 

 mechanical support of the flower (d) and (e) con- 

 siderations of economy must also always be remem- 

 bered. 



It is not possible to give a complete account of these 

 modifications, as the arrangement is never exactly the 



