Prof. Buff on the Electricity of Plants. 135 



whether on the upper or under portions of the stem or branch, 

 and when this injured place was brought into contact with the 

 water of one of the beakers, either immediately or by the inter- 

 vention of wet bibulous paper, while uninjured leaves dipped 

 into the other beaker (it being a matter of indifference what 

 portion of the plant they belonged to), the direction of the cur- 

 rent was always from the wouuded portion of the plant to the 

 leaves. 



Two leaves of the same plant immersed, one into the first 

 beaker, the other into the second, produced no current, or at 

 least none whose direction could be predicted beforehand. If, 

 however, a portion of the surface of one of the leaves was removed 

 and the place brought into contact with the water, this was suf- 

 ficient to generate a current towards the uninjured leaf. Even 

 when the connexion between the liquids was established by one 

 and the same leaf, the place of severance from the tree being 

 kept outside, then by scratching the one or the other of the im- 

 mersed portions, a current could be generated which proceeded 

 unifcrmly fi-om the injured place to the uninjured one. 



Exactly the same deportment as tliat observed in the green 

 leaves was exhibited by blossoms, flowers and fruits. The fresh 

 young bark exhibited the deportment of the leaves. Each un- 

 injured portion was positively electric compared with the root or 

 with a wounded portion of the plant, no matter where the wound 

 was inflicted. 



From these observations we obtain the following rule, which 

 is universally valid : — the roots, and all the interior portions of the 

 plant filled ivith sap, are in a permanently negative condition; 

 while the moist or moistened surface of the fresh branches, leaves, 

 jlowers and fruits are permanently positively electric. 



The external cuticle which embraces the fresh branches and 

 leaves, the epidermis, is known to contain a substance of the 

 nature of wax, which possesses the property of interrupting the 

 transmission of the acid and saline liquids which are contained 

 within the plant, without losing in the same degree the capa- 

 bility of being moistened, or of permitting water to permeate it, 

 and of conducting electricity. Between the moist surface of the 

 plant, therefore, and the liquids in its interior, a definite limit is 

 always present, which however does not interrupt the mutual 

 contact and the connexion necessary for conduction. All the 

 conditions for a permanent electro-motive activity are therefore 

 present, an activity, in virtue of which, as experience teaches, the 

 entire exterior surface assumes positive electricity, while the 

 interior portions, to the roots, and the latter included, assume a 

 negative electric state. 



It might be expected that an equally strong electric excitation 



