98 MR. SOLLY ON THE 



probable influence of electricity on germination. It has, however, 

 been suggested, that as all vegetable soils contain carbonaceous 

 matters which are continually undergoing oxidation, carbonic 

 acid is constantly being found in the soil, under precisely the 

 same circumstances as those under which it is found during the 

 germination of seeds. 



A number of valuable experiments on the influence of electricity 

 of low tension on germination have been made by M. Bec- 

 querel. On causing seeds to germinate under the influence of 

 feeble galvanic currents he observed that those in contact with 

 the copper element of the circle grew faster, whilst those in 

 contact with the zinc element grew less rapidly than similar seeds 

 placed on glass ; the negative extremity increasing, the positive 

 retarding germination. Similar results were obtained with bulbs 

 which, were placed on small frames of zinc and copper, con- 

 nected together in water ; those on the negative frame being found 

 to grow sooner than those on the positive. In these experiments 

 electricity was employed to assist in forwarding the ordinary 

 chemical changes necessary to germination, the plants themselves 

 being in fact regarded as acting like the negative termination of 

 an ordinary voltaic arrangement.* The favourable influence 

 of negative electricity of low tension on germination is attri- 

 buted to the decomposition of saline substances, and consequent 

 evolution of alkaline matter, which assists germination by com- 

 bining with and neutralising the acetic acid always evolved during 

 germination and the growth of bulbs and buds. M. Becquerel 

 also fully considers the action of atmospheric electricity on vegeta- 

 tion, f After observing that tlie earth and atmosphere are always, 

 under ordinary circumstances, in opposite electric states, the 

 equilibrium between wliich is constantly being restored by the 

 agency of mountains, plants, and animals, he states that the clie- 

 mical effects produced by these currents of electricity favour or 

 retard vegetation according to their direction. In the ordinary 

 state of the atmosphere it contains free positive electricity ; the 

 plants therefore are negative, and consequently must manifest 

 an acid reaction on their surface ; and hence, under these circum- 

 stances, the electricity of the atmosphere must facilitate vegeta- 

 tion by assisting the vital force. In the consideration of this 

 part of the subject M. Becquerel also inquires into the influence 

 of electricity on the phenomena of endosmose and exosmose — • 

 effects of heterogeneous affinity, dependent on the attraction of two 

 different fluids for each other, and their power of wetting and 



* Ann. de Chimie et de Physique, lii. p. 240. 

 f Traite Experimentale, iv. 157 — 210. 



