40 THE VITAL FUNCTIONS. 



globules, which adhere to the inner coat of the cell 

 in great numbers, and the presence of which seems 

 to determine the existence, as well as the course of 

 each current : and he inferred from this fact, that 

 the fluid was actuated by a force emanating from 

 these globules, and which he conceived might be 

 electrical. Becquerel and Dutrochet have suffi- 

 ciently proved that it is not due to electricity ; but 

 still the fact of the dependence of the motion on 

 some action of the green globules, remained estab- 

 lished. Donne, however, observed that each of 

 these globules, when detached from the membrane 

 to which it had been adherent, spontaneously 

 revolved rapidly round its axis; a motion which 

 was quite independent of the general circulatory 

 current, and was apparently derived from some 

 inherent power of rotation. All the agents and cir- 

 cumstances which retard, accelerate, or put a stop to 

 the rotation of the current, produce the same effect 

 on that of the individual granules. These observa- 

 tions, which have been confirmed by those of A. 

 Brongniart and Dutrochet, appear to warrant the 

 conclusion that the same unknown power which 

 causes the rotation of the granules when they are free 

 to move, produces a current in the adjacent fluid 

 when the graniiles are fixed, as they are in the 

 natural condition of the plant.. 



§ 7. Excretion in Vegetables. 



It had long been conjectured by De CandoUe, that 

 the superfluous or noxious particles contained in 

 the returning sap are excreted or thrown out by the 



