270 



JOURNAL OF HORTICULTURE AND COTTAGE GAKDENER. 



( October 9, 1873. 



tially decayed, had a crowd of the Millipedes in it. We do 

 not think they caused the tuberless result. Have any of our 

 other correspondents observed such an absence of tubers ? — 

 Eds.] 



EOSE ELECTION. 

 In consequence of an application from one of your corre- 

 spondents I have taken counsel with two or three rosarians 

 whose opinions are of weight, and it seems quite unnecessary 

 to hold an election of all the Roses annually. In this opinion 

 I heartily coincide. It has, however, been suggested that an 

 election of the best Koses introduced in 1870, 1871, and 1872 

 would be useful. The question I would put to ail who have 

 grown any of these Roses is this, Name the best twelve Roses of 

 1870, 1871, and 1872, and underline the best six. To readers 

 of our Journal who have grown any of these Roses, and will 

 answer this question, I shall be obUged. — Joseph Hinton, 

 Warminster. 



EFFECTS OF ELECTRICITY ON PLANTS. 



Does electricity act on plants in the same manner as heat, 

 and does it kill them like a toxical agent ? or is it a disorganis- 

 ing agent, which compromises life by destroying the organs 

 necessary to its maintenance ? This question we propose to 

 examine. 



The effects of electricity on plants have been little studied. 

 In general, observation has been limited to the effects of elec- 

 tricity of high tension from a battery or a thunder-cloud, in 

 which circumstances the plant has always been killed, and the 

 lesions in various organs left no doubt that death was the 

 result of laceration of tissue. 



We have studied the influence of electricity of weak tension 

 from Bunsen couples. It could be gradually increased, and 

 was measured by a galvanometer placed in circuit. The plant 

 chiefly experimented upon was Balsam, Balsamina impatiens, 

 chosen partly because easily procured, partly as being very 

 sensitive to external agents. Its stem is impregnated with 

 juices, which afford a ready passage to electricity, and its deli- 

 cate-tinted flowers indicate by their changes of colour the 

 influence of the current traversing them. 



In our first experiments we employed the current from a 

 single Bunsen couple ; inserting the points of the rheophores 

 in the extremity of the stem, at an interval of two centimetres. 

 After half an hour's passage of the current there was no sen- 

 sible effect ; but the plant, then left to itself, ere long gave signs 

 of enfeeblemeut, and the part above the point where the cur- 

 rent entered, quite dried up. 



The effect was much more rapid, and extended over a greater 

 length of stem, when we used two couples, and placed the point 

 of the rheophore by which the current entered at the lower 

 part of the stem. The plant soon indicated disorder by the 

 drooping of its leaves all along the stem, and, left to itself, 

 soon withered. 



In these experiments the plant was killed through the de- 

 composition produced by electricity in the tissues. Of this we 

 convinced ourselves as follows; — A branch of Balsam experi- 

 mented with bore leaves of a delicate rose colour, and we ascer- 

 tained that this tint was changed to blue under the influence 

 of an alkali such as potash or ammonia. To test whether the 

 current would produce a similar change, we fixed the rheo- 

 phores in a part which was thick with flowers. The flowers 

 near the negative pole took a very perceptible blue tint, proving 

 that the alkaline substances were accumulated at this point, 

 and these substances could only arise from the decomposition 

 of the tissues by the passage of electricity (sufficiently explain- 

 ing the change in the other case). 



We were interested to know if flowers of another colour 

 would also be changed by the current. With this view we 

 chose a Balsam with violet flowers, and subjected it to the 

 action of the pile. Those in the neighbourhood of the negative 

 pole did not change in tint, liut those at the positive took a 

 very perceptible red colour, produced, doubtless, by the trans- 

 ference of some organic acid to this point. These experiments 

 induce the belief that the varied colours observed in flowers of 

 the same species arise from the presence of some acid or basic 

 substance generatedin the tissue of the flowers, and capable of 

 altering their hue. 



But the most interesting result, for us, in these experiments 

 is, that heat and electricity do not cause death in plants by the 

 same action. Heat acts like a poison, paralysing and destroy- 

 ing the irritability of the cellular and fibrous tissue of plants, 



while electricity disorganises their tissues, and thus prevents 

 them from fultilUng their functions. 



We further examined the effects of induction currents. The 

 effects of these on man and animals have of late years been 

 extensively studied, and medical science has found in them a 

 vahiable agent, especially for oases of paralysis of the nervous 

 system. 



Our first experiments were made on a plant, the movements 

 of which present some analogy to the spontaneous movements 

 of animals — viz., the Sensitive-plant, Mimosa pudica. The 

 effects strikingly resembled those on animals. An electric 

 action, slight and short, suffices to close the leaflets of the 

 plant, and to depress the petioles all along the stem ; but after 

 some time the leaves resume their first position, and do not 

 appear to have suffered. If the commotion is powerful and 

 continued for some time, the plant does not thus recover, but 

 dies, its tissue not appearing, however, to have undergone any 

 change. 



These results were confirmed by those obtained from more 

 common plants. We selected a vigorous and well-developed 

 Balsam, the stem of which bore leaves, flowers, and fruit. 



We examined first the effect on the leaves, connectiug the 

 base of the petiole with one of the wires of a Rhumkorff coU, 

 and the summit of the leaf with the other. The current was 

 from a single Bunsen couple, and the coil, though small, could 

 give pretty severe shocks and bright sparks. 



With these conditions we observed after a few minutes 

 that the leaf lost its rigidity, the petiole inclining towards the 

 stem, and the leaf looking like one which suffered from lack of 

 moisture. Left to itself it resumed its usual appearance ; the 

 action of the current had only weakened the tonicity of the 

 tissues, but had not caused death. 



We experimented similarly on another leaf, but during a 

 longer time (about a quarter of an hour). It did not afterwards 

 recover, but dried up — a proof that the duration of the commo- 

 tion has an influence on the effect produced. 



Next we made the current act on a fully-developed flower. 

 The effect on the tissues was more speedy and obvious than in 

 the preceding case. The peduncle bent towards the stem, and 

 the corolla changed in colour — evident proof of a profound alter- 

 ation in the tissues ; for the flower, at first of a lively red, as- 

 sumed a blue colour under the current. This experiment was 

 repeated in a great number of flowers, and always with like 

 results. 



We also made the induction current act on the entire stem 

 of the Balsam, connecting one of the wires to the lower part, 

 and the other to the extremity. The current left throughout 

 the stem traces of its passage. At first the plant did not appear 

 to have undergone any change ; but after some time we observed 

 that the extremity, formed of tender and pulpy matter, became 

 inclined, as if aff'ected in its organisation. The flowers changed 

 colour, and the fruits, which had not yet reached maturity, 

 were burst, projecting to a distance the seeds they held. The 

 Balsam stem, thus acted upon for a quarter of an hour, was, in 

 reality killed, and in a few days completely withered up. It 

 appeared as if struck by lightning. 



]3irds also were killed by the induction current. 



The current which thus acts with such energy on the soft 

 and pulpy parts of plants exerts less sensible influence on their 

 ligneous parts. We repeated the foregoing experiments on a 

 leaf of Rose Bay, Nerium Oleander, and it was not perceptibly 

 affected; whereas, en operating with a branch which bore 

 several flowers, we observed these within, and on the following 

 day they had the aspect of having been scorched by the sun. 



We repeated the same experiment on a stem of Basil covered 

 with leaves and flowers. The stem and the leaves resisted, but 

 the flowers felt the effects of the electricity, for ere long they 

 fell off. The same results were obtained with a flowering stem 

 of Lavender, and with a branch of Fuchsia. 



From these experiments it appears sufficiently established 

 that the induction current produces the effect of a disorganis- 

 ing agent on the organs of plants only when, by reason of the 

 softness of their tissues, and the large quantity of water im- 

 pregnating them, it is propagated with ease in their interior ; 

 and that it has no appreciable action on solid and resistant 

 tissues. Still, if several couples were employed instead of one, 

 or if the coil were more powerful, or the action prolonged con- 

 siderably, there is little doubt that the most solid parts of plants 

 would be disorganised by the current. 



Next as to fruits and seeds. We selected an Apple on a 

 branch which bore several nearly ripe. The extremities of the 

 conducting wires being applied to it, the current was allowed 



