THE HONEYBEE AND BEES IN GENERAL 263 



constituted so as to prevent self-pollination and the visitations 

 of unsuitable insects. On the other hand, they are so formed as 

 to secure visits from insects that fly rapidly, and enter many 

 flowers, thus insuring the wide distribution of pollen. The bees 

 are among the most important of the pollinizing insects. They 

 are especially valuable near fruit trees, since it has been demon- 

 strated that orchards containing colonies of bees are more pro- 

 ductive than neighboring orchards without bees. 



Some of the most interesting arrangements for the securing of 

 cross-pollination are found among the flowers of the orchids. 

 For example, the common lady-slipper (Cypripedium) is adapted 

 to the visitations of bumblebees. The flower has a conspicuous 

 pouch with an opening on the upper side of the inner end, over 

 which hangs a flap possessing two anthers and a stigma. The 

 bee forces its way into the pouch (Fig. 148, A) and sucks up the 

 nectar contained within (B). In escaping from the pouch it 

 brushes its back first against the stigma (C) and then against the 

 anther (D). Any pollen present upon the bee's back is brushed 

 off upon the stigma during its escape, and a new supply is then 

 gathered from the anther. The next orchid visited receives this 

 pollen upon its stigma, and adds a new burden to the bee's load. 

 The bumblebee thus is obliged to transfer pollen from one plant 

 to another while gathering nectar (203). 



THE COLORS OF FLOWERS. Many scientists believe that the 

 brilliant colors of many flowers attract bees and other insects, 

 and are therefore instrumental in causing cross-pollination. It is 

 further claimed that the bright colors themselves are the result 

 of the visits of insects, since those flowers that happened to be 

 more brightly colored would be more certain to attract insects, 

 and therefore more liable to be pollinated and produce seed. The 

 selection of the more brightly colored flowers for a sufficient 

 number of years would result in the survival of plants which 

 tend to produce more highly colored flowers. This entire theory 

 of the origin of the colors of flowers because of the visits of in- 

 sects seems to depend upon the factor that attracts the insect to 



