Flowers. 



183 



next traverses the crystal cone k, which is also a trans- 

 parent lens. The nerve tissue /, ni, and n, is in immediate 

 communication with these lenses, and transmits the light 

 stimuli to the main optic nerve, and 

 thence to the nerve ganglia which 

 represent the brain. 



The compound eye of an insect 

 does not form an image in the same 

 manner as does the human eye, in 

 which divergent rays of light from 

 any point are brought to a focus on 

 the retina, and a relatively bright 

 inverted image is formed. Insects 

 can, therefore, not see as well as we 

 can. This appears to be borne out 

 by the action of insects, which do 

 not seem to appreciate the forms of 

 objects well until they are quite near 

 to them. Fjg, gg 



Since the main object of insects' Diagram of the compound Eye 



of an Insect. A, a surface 

 view of some of the simple 



eyes united to form a com- 

 pound eye. B, a longitu- 

 dinal diagram of three 

 simple eyes. See text. The 

 image formed is said to be 

 a mosaic, each simple eye 

 contributing a distinct por- 

 tion. After Lubbock. 



visiting flowers is that of obtaining 

 food for themselves or their young, 

 their relations to flowers will be 

 better appreciated when the con- 

 struction of their food-gathering ap- 

 paratus is understood; and for this 

 purpose the bees and butterflies will 

 be chosen for examples, because they represent two kinds 

 of insects which are most important to flowers. 



135. Relation of Butterflies to Flowers. — Butterflies sip 

 the nectar only, and do not make use of the pollen ; al- 

 though in getting the nectar they incidentally transfer 

 pollen from flower to flower. They do not carry away 



