198 PLANTS EXCITED BY SUNSHINE. 



the ordinary processes of vegetable growth are at- 

 tended with a disturbance of electric equilibrium, 

 which is manifested when the bodies in which it 

 takes place are effectually insulated. " Several 

 pots filled with earth, and containing different 

 seeds, were placed on an insulated stand in a room, 

 the air of which was kept dry by quick-lime; and 

 the stand was placed in connection with a con- 

 densing electrometer. During germination no 

 electric disturbance was manifested ; but the seeds 

 had scarcely sprouted when signs of it were evi- 

 dent ; and when the young plants were in a com- 

 plete state of growth, they separated the gold 

 leaves of the electrometer half an inch from 

 each other." 



It was calculated by him that a vegetating sur- 

 face of one hundred square metres in extent pro- 

 duces in a day more electricity than would be 

 sufficient to charge the strongest battery ; and he 

 not unreasonably considered that the growth of 

 plants may be one of the most constant and pow- 

 erful sources of atmospheric electricity. 



The disengagement of vapor from the surface 

 of the leaves alone would be sufficient to produce 

 such a disturbance, as the fluid from which it is 

 given off is always charged with saline and other 

 ingredients; and the gaseous changes which are 

 effected by the leaves upon the oxygen and car- 

 bonic acid of the atmosphere, may be regarded 

 as additional sources of its development. 



