PLANTS AND ELECTRICITY 



weather its leaflets hang limp and numb from the leaf-stalk 

 all day. In fine weather they are spread out horizontally. 

 On a fine sunny afternoon its leaflets may sometimes take a 

 mid-day sleep, for they hang loosely down in the same way 

 that they do in cold, wet weather or at night. 



But in the Woodsorrel these movements are not for pro- 

 tection against grazing animals. 



There are other examples amongst plants of a distinct 

 sudden movement which begins whenever part of the plant 

 is touched. The movements of tendrils have been already 

 referred to. The Venus' Fly Trap and the Sundew will be 

 mentioned when we are discussing Insectivorous Plants. 

 There are also several flowers in which the stamens suddenly 

 spring up when they are touched by an insect (Barberry, 

 Centaurea, and Sparmannia), and in Mimulus the style-flaps 

 close when touched (see p. 70). 



All these cases seem to involve some sort of mechanism 

 which replaces the nervous system of animals. 



No very definite laws have yet been discovered as to the 

 way in which plants are affected by electricity, but enough is 

 known to show that there are many interesting discoveries in 

 prospect. 



Professor Lemstrom has made some interesting experiments 

 in the Polar regions which go to show that the rich develop- 

 ment of plant life in that desolate region may be connected 

 with the peculiar electrical conditions of the Polar atmo- 

 sphere ; the aurora borealis, which is a common phenomenon 

 there, being also produced by those conditions. 



Several writers have claimed that slight electric shocks 

 given at frequent intervals help the growth of plants and 

 especially quicken the germination of seeds, but it can 

 scarcely be said that this has been proved. 



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