CHAP. Xir. IN PLANTS DUBING VEGETATION. 161 



or moistened surface of the fresh branches, leaves, flowers, 

 and fruits, are permanently positively electric." .... 

 He considers that " the electro-motive action arises 

 from the moist surface of the plant on the one hand, 

 and the liquids which are in its interior on the 

 other.'' 



The results of these inquirers would lead us to 

 suppose, that the effect upon the needle is due to 

 what may he termed secondary actions, viz. to the 

 reaction of the different vegetable juices upon each 

 other, and to the reaction of the fluids upon the 

 surface of the platinum electrodes. Th« very fact, 

 however, that a difference in the fluids exists, proves 

 also that a force capable of causing this difference 

 must likewise exist; and the question, naturally 

 arises, are not these primary actions accompanied 

 with the developement of electrical actions ? 



The primary actions I refer to are those of secretion, 

 nutrition, and absorption. Now as the leaves and the 

 roots perform some of the most important functions 

 in plants, it appeared probable that it would be in 

 these organs that we might obtain a solution of our 

 problem; and the two following questions now oc- 

 curred : 1st, What would" be the effect if the external 

 surface of the leaf, and the sap flowing from it, be 

 formed into a circuit? and, ^dly, What would be the 

 effect if the external surface of the root (the spon- 

 gioles) and the fluid ascending from it be formed 

 into a circuit? 



