FAMILIAR LESSOXS IX BOTAXY. 



of the *'• Loves of the Flowers/' claims that the mimosa 

 knows even the approach of rough weather : 



" Weak with nice sense the chaste mimosa stands, 

 From each rude touch withdraws her timid hands ; 

 Oft as light clouds o'erpass the summer glade, 

 Alarmed, she trembles at the morning shade. 

 And feels alive through all her tender form 

 The whispered murmui-s of the gathering storm." 



195. If you but touch the pericarp of the balsam it 

 bursts, scattering its contents in the most irritable manner. 

 The Desmodium gyraiis possesses the most remarkable 

 powers of spontaneous movement. Its branchlets some- 

 times moving together, then again one solitary leaf, then 

 two or more, then perfect quiet will reign, perhaps to be 

 broken by every leaf from base to apex putting themselves 

 into the most diverse and fantastic motions. Plants also 

 sleep, particularly those belonging to the pinnate leaf tribe 

 so common in Louisiana and Texas. Some exhibit this 

 peculiarity much more than others. The retamaand wee- 

 sachie, for instance, seem to sink to rest at night, and 

 arouse to life again with the morning sun. 



196. In witnessing these various phenomena so analogous 

 to similar exhibitions of animal life, we sometimes feel 

 almost inclined to fall into Darwin's theory, that plants 

 have a nervous system similar to that in the animal econo- 

 my. He goes forther, and compares the sap to the blood, 

 pores to lungs, spoiigioles to mouths, woody tissue to bone, 

 cellular tissue to fiber, pith to marrow, etc. But this is 

 fanciful and overstrained. Botanists of later days have re- 

 jected all such theories, and place these vegetable phe- 

 nomena under the general head of irritability. This they 

 refer to three heads, as it is produced by the atmosphere. 



195. What of the pericarp of the balsam? The Desmodium gyrans ? Of other 

 plants ? 



196. In witnessing these phenomena, what are we inclined to do ? Where do 

 botanists place these phenomena ? How divided ? 



