THE FEELINGS OF PLANTS 109 



doubtful whether the plant is more sensitive in 

 this way than the Mimosa. A young specimen, 

 which the writer had in his possession, evinced 

 considerable leaf agitation during the progress of 

 a thunderstorm. Almost all these sensitive plants 

 are very much affected when exposed to the 

 vapours of an anaesthetic ; in this instance the 

 foliage assumes the position which it takes up 

 at night. 



The Telegraph Plant (Desmodium gyrans) has 

 well been called one of the most curious in the 

 world. Certainly it presents a problem which 

 has completely baffled all scientists. The leaves 

 of this species are divided into three parts, con- 

 sisting of a large leaflet and two smaller lateral 

 ones. It is these latter which offer a strange 

 phenomenon, and one which is not at all easy to 

 explain. Practically throughout the whole of their 

 existence these leaflets are in motion, executing 

 little jerks, which suggest the movements of the 

 seconds hand of a watch. When one of the 

 leaflets rises the other descends, each in its turn 

 describing a kind of elliptical course. 



These movements occur throughout the life 

 of the plant, although the greatest activity is 

 evinced by the leaflets during humid days when 

 they are under the influence of bright sunshine. 



