■V *? 



93 On Electricity in Plants^ a7id on Vegeto-terrestrial Currents. 



Kind of electricity. Angle of de\-iation. 



o ^ Leaves of lindetij . . + 



^* elder. 



30 



M C Leaves o^ orange, 

 * " linden, 



T 



10 



50^ 



cr 



^ C Leaves of orange, . . + 

 ) " walnut, • 



In the preceding pages I have treated of the effects obtained 

 with a transverse section of a stem ; it remains to speak of the 

 electric effects observed in a longitudinal section. Let a and h 

 be two points in the green part of the parenchyma of a stem at 

 different distances from the ground and several decimeters apart, 

 a being the upper and b the lower. On introducing transversely 

 into the parenchyma at each of these points one of the platinum 

 needles, there is immediately apparent an electric current, the di- 

 rection of which evinces that the needle at h gives negative elec- 

 tricity, and that at a positive. Hence the parenchyma sap at points 

 thus distant has not the same composition: at the lower point J, 

 as it contains less oxygen than at a, since it loses more and more 

 oxygen in passing along the green part of the parenchyma, it 

 ought to disengage negative electricity. 



A current is also obtained on establishing a cotmection between 

 the cambium and the leaves, which may be effected, by placin 

 one needle between the bark and the wood, and the other in a 

 mass of superimposed leaves all being a part of the plant. On 

 closing the circuit, acurrent at once appears going from the in- 

 terior to the exterior^ as in the case when the needle which is 

 here in the leaves is placed in the parenchyma while the other is 

 in the cambium ;'"lhe result corresponds to the nature of the sap 

 which circulates in the leaves and parenchyma. We give beyond, 

 the consequences from the facts that have been presented. 



IL On the Electric state of the earth relatively to that of Plants, 



As the earth is in direct and permanent communication with 

 plants by means of the roots, it ought to participate in the elec- 

 tric state resulting from the different elaborations taking place in 

 their tissues. This question bears upon the electric state of the 

 atmosphere, and nothing should be omitted which can serve to 

 elucidate it. 



It is known that the earth is in a constant state of negative 

 electricity, whilst the air, when calm and without clouds, contains 

 an excess of positive electricity whose intensity goes on increas- 

 ing as we ascend above the surface of the earth. The earth and 

 atmosphere are therefore ordinarily in two contrary electric states. 

 These states change during storms or when clouds appear ; for 



