OiiAP. VII. FIKST-rORMED LEAVES. 417 



the interesting fact of the pulvini or organs of move- 

 ment of these little leaflets, not having been reduced 

 nearly so miich as their blades — taking the large 

 terminal leaflet as the standard of comparison — givae 

 us probably the proximate cause of their extrao:dinaiy 

 poller of gyration. 



