164 OUEEENT ELECTBEOITY CHAP. XH. §. 1. 



Another fact worthy of notice may be mentioned. 

 As the galvanometer was frequently obliged to be 

 moved into the neighbourhood of the plant, it would 

 sometimes happen, from the altered position of the 

 instrument, that the plane of the coil would be in 

 the reverse direction of that of the needles to which 

 it had been previously ; hence contradictory results 

 would very readily be supposed to be obtained. 



To avoid unnecessary repetition, I shall generalize 

 the results that were obtained in the following 

 experiments. They were conducted in the same 

 manner as in the first experiment, and upon leaves 

 of different varieties of the following plants : 

 cucumber, vine, lettuce, cabbage, nasturtium, con- 

 volvulus, rose, ivy, hop, walnut, geranium, fuchsia, 

 strawberry, bean, apple, ficus elastica, ficus carica, 

 lemon, orange, oleander, eutaxia, camellia, mesembry- 

 anthemum, lily, marvel of Peru, pirus japonica, 

 tropseolum, wistaria, elder, sycamore, hollyhock, 

 arum, hydrangea, thistle, and dahlia. In some the 

 effects were null, in others but slight; the greatest 

 effect obtained amounted to about 2° or 3° ; the 

 electrode in contact with the sap, positive. The most 

 satisfactory results appeared with the firm, compact 

 leaves, such as the camellia, vine, elder, and syca- 

 more, and when the electrode was in contact with 

 the imder surface. It frequently happened, that, in 

 experimenting with different leaves of the same 

 plant, effects might be obtained with one leaf but 

 not with another, although in other respects perfectly 



