198 STUDY OP COMMON PLANTS. 



are any lines or dots likely to serve as path 

 pointers. Compare the color of the standard of a 

 number of flowers. 

 2. Observe the form and structure of the wings. Re- 

 move one and sketch its outline. In an unin- 

 jured flower, notice -particularly how the wings 

 are fitted to the keel and standard. 



IV. With a pencil, or other instrument, push the wings 

 downward with some force, imitating the action of a heavy 

 insect. Repeat the operation on different specimens until 

 its result is clearly seen. 



V. See if you can understand how it is that the wings 

 and keel return to their position when the pressure is 

 removed, and whether there is any advantage in this. 



VI. Examine next the structure and mechanism of the 

 essential organs. 



1. Remove the floral envelopes from the side of the 



flower, leaving the other parts undisturbed. The 

 stamens and pistil can now be studied to advan- 

 tage in their natural position. 



2. Count the stamens. Are they monadelphous or dia- 



delphous ? Are they all alike ? Compare those 

 of flowers about to open with younger and older 

 ones. 



3. Look at the end of the keel of uninjured flowers. 



Where is the pollen stored after the dehiscence 

 of the anthers ? Examine and describe the mech- 

 anism by which it is pushed out when the keel is 

 opened. 



4. Observe next the shape of the pistil, the direction 



taken by the style, and the surface of the latter as 

 seen under a lens. 



