218 f)e Barton's 



transition from blood-sucking to honey-sucking. 

 Sometimes in a single species the females, which 

 require more nourishment, are blood-suckers, 

 while the males seek honey only. In Paltosto- 

 ma torrentium (Blepharocertdce), two different 

 kinds of females exist together, one blood-suck- 

 ing, the other honey-sucking ; while the males 

 are all alike, and all feed on honey. In like 

 manner, Miiller states that several flowers seem 

 to have acquired an offensive smell correlative 

 to the habits of certain anthophilous flies which 

 at times feed on putrid flesh and excrement as 

 well as flowers. Tiny species of midges, which 

 people dark corners by day and leave them in 

 the evening, are regular fertilizers of many flow- 

 ers which afford somber hiding-places for their 

 visitors. 



In almost all bees highly specialized for fer- 

 tilization, the body is more or less thickly clothed 

 with long, feathery hairs, that in many flowers 

 become dusted, without any direct effort, with a 

 considerable quantity of pollen, which is then 

 cleared off by means of the tarsal brushes. 

 Easily as the hairs take up pollen, they return it 

 with equal ease to viscid or rough stigmas. 



So greatly has the hirsute covering of the 

 hind-legs increased, and so perfect has become 

 the development of tarsal brushes in the exceed- 



