244 PIIYTOXOMY. 



Even ilie blighting of corn in low lands, by means of power- 

 ful storms of lightning, shews the operation of the exhausting- 

 stimulus, which the discharge of atmospherical electricity af- 

 fords. In the same manner Buck-wheat fails to be produc- 

 tive when it has been exposed to lightning ; (Thaer, Grund- 

 satze der Rationellen Landwirthschaft.) 



We cannot state, in opposition to this, that artificial elec- 

 tricity from a machine produces little effect on very fine leaves, 

 when tliey are disposed to sleep, because this change of state 

 is one of those vital phenomena which depends principally 

 upon the effects of light. It is certain that seeds germinate 

 more actively, and that branches put forth buds more early, 

 when they are electrified. 



373. 



The kind of electricity which is excited by two bodies of 

 different susceptibilities of oxydation, with intervening moist- 

 ened conductoi*s, and which we call Galvanism, or the Gal- 

 vanic Activity, has a powerful influence upon the whole of na- 

 ture, particularly upon organized nature, and, therefore, upon 

 the vegetable world. Indeed, neither simple galvanism, nor 

 the voltaic pile, has any remarkable influence on the motions of 

 sensitive plants ; but it has been })roved that still the germina- 

 tion of seeds is very much promoted by the positive pole of 

 the voltaic pile, when no extraordinary discharge takes place. 

 On the contrary, the negative pole of the voltaic pile exhausts 

 in every case the vital activity of plants. 



We are more generally concerned, howe\'er, witli the pro- 

 cess of natural galvanism, which incessantly takes place in 

 every organized body, where opposite principles are evolved, 

 where an excitation of the elementary matters takes place, 

 and where layers of different capacities of oxydation are con- 

 nected by moistened conductors. In all these cases, that ac- 

 tion takes place which we call Galvanic, and produces effects, 

 wliich chemistry can then only in some degree imitate, when 

 she avails herself of artificial galvanic batteries. 



The organic perspiration through impervious coverings, 

 whicli we have often spoken of, is a \ ital function, which Wol- 

 kston has successfully imitated at the pole of the voltaic pile. 



