230 FREAKS. OF PLANT LIFE. 



duced by its rapid evaporation. It may be stated, 

 that two or three drops placed on the leaf in the 

 ordinary way had no effect at all. A few days after, 

 similar trials were made in the Botanic Garden, 

 Chelsea, on some plants of the same species, grown 

 in a colder house, and which were ' short-jointed,' 

 and altogether firmer in texture. In these instances 

 no other effect was produced then the death of the 

 leaf. The other case was a Maranta, also growing 

 in a stove, and in which the application of ether 

 spray to the tip of a leaf caused it to roll up on to 

 the underside, like a roll of paper. In the young 

 state the leaves of this plant are rolled lengthwise, 

 but the effect of the ether was to cause the leaf to 

 roll up along the under surface, from the tip towards 

 the stalk." 



Returning from this digression to the special sub- 

 ject of this chapter, it may be intimated that tempe- 

 rature and a healthy condition are important factors 

 in the manifestations of irritability. The tropical 

 wood-sorrel {Oxalis sensitivd), which is remarkably 

 sensitive in countries where it grows naturally, 

 scarcely exhibits this peculiarity, even when grown 

 in hot-houses, in this country. Both Desmodium 

 gyrans and Mimosa pudica show an evident increase 

 of susceptibility with an elevation of temperature. 

 A plant of the Mimosa, carried about in his carriage 

 by Desfontaines, although at first exhibiting its usual 



