O/iAP. VII. FIKST-FOEMED LEAVES. 417 



ttie interesting fact of the pulvini or organs (jf move- 

 ment of these little leaflets, not having been reduced 

 nearly so much as their blades — taking the large 

 terminal leaflet as the standard of comparison — gives 

 as probably the proximate cause of theii" extraordinary 

 power of gyration. 



