INFLUENCE OF ELECTRICITY ON VEGETATION. 87 



and in all growing plants, is then shown ; and lastly the effects 

 produced by artificial electricity are described, and compared 

 with those which are observed in nature. In the second part 

 of the book, the effects produced by electricity are more mi- 

 nutely examined. The experiments of Nollet and Jallabert are 

 described and confirmed by Bertholon's own results ; he observed 

 in addition, that interrupted electrification appeared to have more 

 influence than when continued, in accelerating vegetation. On 

 the growth of leaves and flowers, he quotes the experiments of 

 Maimbray, Nollet, Jallabert, and also Muschenbroek, who had 

 arrived at the same results as these philosophers. This part con- 

 cludes with some curious chapters on the colours, odours, and 

 tastes of fruits and flowers, on the development of which he 

 thinks that electricity exerts a very remarkable influence. 

 Fruits nearly ripe on being electrified were found to acquire the 

 odour and taste of ripeness sooner than others not electrified ; 

 and flowers or plants just coming into blossom arrived sooner 

 at perfection, and the colours were more brilliant than is ordi- 

 narily the case ; when plants in flower were electrified the blos- 

 soms were observed to become more brilliant in colour, and of 

 a richer and more delicate tint, than other flowers of the same 

 kind of plant. All these experiments were made with positive 

 electricity, and there is accordingly a chapter specially directed 

 to the consideration of the effects produced by negative elec- 

 tricity ; these are, for the most part, the reverse of those produced 

 by positive : germination is retarded, the growth and formation 

 of the leaves is checked, the development of fruit and flowers, 

 and the secretion of colouring and odorous matters, is impeded ; 

 and these effects, he states, may be observed by experiments on 

 the small scale as well as by carefully watching the electric 

 condition of the atmosphere on a large scale. 



The third and last part of M. Bertholon's book contains the 

 practical applications of those principles which he endeavours to 

 deduce from experiments and theoretical reasoning ; namely, 

 the means of increasing the natural supply of electricity to 

 plants, when it is deficient ; the means of diminishing it when too 

 abundant ; the application of electricity in protecting plants from 

 the attacks of those insects to which they are liable, and in pre- 

 serving them from the effects of various diseases. For the first of 

 these objects he proposes an instrument which he calls an electro- 

 vegeto-meter, which consists of a well-insulated pointed con- 

 ductor, attached to a high wooden pole firmly fixed in the 

 ground, and well connected with a number of metallic points 

 placed points downwards, on a suitable support above the surface 

 of the ground, and so arranged that the series of points being 

 connected with the upright conductor by a chain, may be carried 



