170 CUBBENT ELECTBICITT CHAP. XTX. §. H. 



from the plant to the soil, which is thus positive with 



relation to it." " The superficial layers of the 



soil are frequently positive relatively to those which 

 surround the spongioles.'' 



In several experiments, the facts ohserved hy 

 Becqdeeel and Waetmann were ohtained, viz. the 

 electrode in contact with the soil was positive to that 

 in contact with the plant ; but that the effect was in 

 a great measure due to the soil, was shewn thus, — 

 both electrodes were inserted into the soil, when 

 one was found generally to be positive to the other. 

 To obviate this difficulty, the electrode employed to 

 be inserted into the earth was coated with sealing 

 wax to the extent of three inches, leaving the ex- 

 tremity exposed for about a quarter of an inch. 



Several experiments were performed upon plants, 

 such as different kinds of geraniums, fuchsias, 

 balsams, antirrhinums, lophospermums, and vege- 

 table marrows, growing in pots, in the following 

 manner : The coated electrode was inserted into the 

 soil, and a notch having been cut in the stem 

 about an inch above the earth, or the stem entirely 

 removed, the other electrode was then brought into 

 contact with the divided surface ; sometimes the 

 electrode was inserted into the stem; the general 

 result was as follows : in a very few instances, with 

 a lophospermum and an antirrhinum, and one or 

 two geraniums, the electrode in contact with the trunk 

 of the plant, with the sap, was found to be positive 

 to the other; in many instances no decisive effect 



