36 INTERRELATIONS OF PLANTS AND ANIMALS 



secreted. It is principally this food substance, later made into 

 honey by bees, that makes flowers attractive to insects. 



The Essential Organs. A flower, however, could live without 

 sepals or petals and still do the work for which it exists. Certain 

 essential organs of the flower are wiuiin the so-called floral envelope. 

 They consist of the stamens and pistil, the latter being in the center 

 of the flower. The structures with the knobbed ends are called 

 stamens. In a single stamen the boxlike part at the end is the 

 anther; the stalk which holds the anther is called the filament. 

 The anther is in reality a hollow box which produces a large 

 number of little grains called pollen. Each pistil is composed of 

 a rather stout base called the ovary, and a more or less lengthened 

 portion rising from the ovary called the style. The upper end of 

 the style, which in some cases is somewhat broadened, is called the 

 stigma. The free end of the stigma usually secretes a sweet fluid 

 in which grains of pollen from flowers of the same kind can grow. 



Insects as Pollinating Agents. Insects often visit flowers to 

 obtain pollen as well as nectar. In so doing they may transfer 

 some of the pollen from one flower to another of the same kind. 

 This transfer of pollen, called pollination, is of the greatest use to 

 the plant, as we will later prove. No one who sees a hive of bees 

 with their wonderful communal life can fail to see that these insects 

 play a great part in the life of the flowers near the hive. A famous 

 observer named Sir John Lubbock tested bees and wasps to see 

 how many trips they made daily from their homes to the flowers, 

 and found that the wasp went out on 116 visits during a working 

 day of 16 hours, while the bee made but a few less visits, and 

 worked only a little less time than the wasp worked. It is evident 

 that in the course of so many trips to the fields a bee must light on 

 hundreds of flowers. 



Adaptations in a Bee. If we look closely at the bee, we find the 

 body and legs more or less covered with tiny hairs ; especially are 

 these hairs found on the legs. When a plant or animal structure 

 is fitted to do a certain kind of work, we say it is adapted to do that 

 work. The joints in the leg of the bee adapt it for complicated 

 movements; the arrangement of stiff hairs along the edge of a 

 concavity in one of the joints of the teg forms a structure well 



