96 MR. SOLLY ON THE 



tation, but at the same time does not attribute to it those verj' 

 marked effects described by Bertholon ; shrewdly remarking, 

 when speaking of the influence of thunder-storms and electric 

 rains on plants, that the effects observed cannot be wholly pro- 

 duced by electricity. Senebier, in his ' Physiologie Vegetale,' 

 1801, after referring to the various statements of different 

 authors, observes, that it appears to him more probable that 

 electricity does not favour vegetation than the contrary ; he 

 however admits that the question is by no means decided. A 

 similar view of the subject is taken by De Candolle, whose 

 experiments led him to attribute little effect to the action of 

 electricity on plants. 



A number of experiments were made early in the present cen- 

 tury, and shortly after the discovery of voltaic electricity, to 

 ascertain its influence upon various organic substances ; but there 

 appear to be no recorded experiments on seeds or growing vege- 

 tables before 1806, when Davy published some interesting ob- 

 servations on the subject.* He observed that seeds placed in 

 pure water in the positive part of the circuit, germinated much 

 more rapidly than under ordinary circumstances ; but that in the 

 neo-ative part of the circuit they did not germinate at all. In 

 explanation of this experiment he remarks that without sup- 

 posing any peculiar effects from the different electricities the phe- 

 nomenon may be accounted for from the saturation of the water 

 near the positive metallic surface with oxygen, and that near the 

 negative one with hydrogen ; though at the same time he does 

 not think it impossible that some effect may be due to the elec- 

 tricity. Davy also describes some experiments in which grow- 

 ing plants were made the medium of connexion between the two 

 extremities of the battery : in one case, a plant of mint was soon 

 killed, but another, after ten minutes, remained uninjured ; lime 

 and fixed alkali was found at the negative extremity, whilst 

 chlorine and sulphuric acid had collected at the positive extre- 

 mity of the battery. 



The experiments of Davy were received by Du Petit Thouarsf 

 as evidence of the great influence of electricity on vegetation. 

 He believed that plants contained two distinct galvanic arrange- 

 ments ; one acting vertically through the woody fibres, the other 

 horizontally through the medullary rays: to the influence of 

 these opposite but independent currents he attributed the prin- 

 cipal phenomena of vegetation. Observations on the influence 



* Philosophical Transactions, 1807. Elements of Agricultural Chemistrj', 

 p. 37. t Essais sur la Ve'ge'tation, 1809, ix" Essai. 



