314 PRESENT STATE OF ORGANIC ELECTRICITY. 



It remains to be determined liow far the single transverse 

 system of electrical currents in either direction, in certain 

 roots, and in tubers, depends upon the disappearance of the 

 central or peripheral elements of the axis. 



On Currents in Leaves. — The relations and functions of the 

 leaf indicate the probable direction of the electrical currents 

 which may exist in it. 



Becquerel's '"' observations lead to the conclusion that cur- 

 rents set from the cambium to the parenchyma of the leaf ; 

 while at the same time it is negative in relation to the pith 

 and wood of the branch and stem. He states that the leaves 

 comport themselves as the green part of the parenchyma of 

 the bark — that is to say, the sap which circulates in their 

 tissues is negative in relation to the wood, pith, and soil ; and 

 positive in relation to the cambium. 



M. Wartmann-f- states that in most leaves the currents 

 proceed from the limb of the leaf to its veins, and to the 

 central parts of its petiole, and of the stem. 



This centripetal current attributed to the leaf by Becquerel 

 and Wartmann is evidently referable to the central or de- 

 scending axial current of the plant ; while the centrifugal 

 current alluded to by the former belongs to the superficial 

 transverse system, or that between the inner and outer aspects 

 of the bark. 



Tlie Electrical Condition of the Flower. — From the energetic 

 actions and rapid development of the flower, a considerable 

 amount of electrical disturbance is to be expected in it. 

 Various observers have ascertained the remarkable elevation 

 of temperature which occurs during the development of this 

 part of the plant ; and the important chemico-vital actions 

 which take place in it must certainly excite corresponding 

 electrical phenomena. 



* " Recherclies sur les causes qui degagent de I'electricite, " etc. — Mem. de 

 I'Aead. de Sciences, torn, xxiii. 



+ BiUiotMque Universclle de Geneve, torn. xv. 



