CROSS-FERTILIZATION OF PLANTS. 



269 



upon one of the graceful sepals and his weight is just sufficient to separ- 

 ate it from the closely covering carpel. The bumble bee then wedges 

 himself in between the slowly opening part and, by stretching his long 

 tongue to its full length draws the nectar from its deep well. The true 

 honey guides are on the upper surface of the petal. The cover is a style 

 and bears the stigma on a shelf like projection just where the bee will 

 rub his head and thorax in wedging himself in. The stamen rises and 

 bears an anther at the point where it wil rub the pollen into the thoracic 

 hairs of the bee. Why is not this same pollen left on the stigma when 

 the bee backs out? If the stigma shelf is rubbed with the finger it opens 



Fig. 30. 



outward as by a bee in entering, and closes when rubbed the opposite 

 way. Thus the pollen gathered from this flower will be transferred to 

 some other flower. The blue flag teaches us several lessons in adapta- 

 tion. All of the irregular flowers are peculiarly shaped with reference 

 to their insect visitors. They are a source of never ending speculation. 

 Protective closure to keep out rain and unwelcome insects has been 

 mentioned earlier. The hanging position of many flowers serves the 

 same purpose. Many flowers have a movement of parts in addition to 

 this closing, some of which are of great interest. My attention was first 

 called to a closing of the lips of the stigma in the catalpa. Near the 

 station, at Big Fork, is a swampy place where many interesting plants 



