82 



EFFECT OF ELECTRICITY ON PLANTS 



germinated earlier. The growth of the treated 

 seeds, moreover, exceeded that of the normal. 



Paulin erected poles in the middle of his experi- 

 mental plots, which supported a collector composed 

 of numerous copper wires. An insulated wire con- 

 nected the collector with an iron wire buried in the 

 soil. He asserted, as a result of his experiments, a 

 gain of 33^ per cent in the production of potatoes. 

 Jodro experimented in a similar way. However, 

 he connected his collector, which was on a pole 35 

 feet high, to a wire attached to zinc plates in the 

 soil. He obtained an average increase of 25 to 50 

 per cent, and in some instances nearly 100 per cent. 



Maccagno's method was somewhat diffei'ent from 

 the preceding one. He attached wires directly to 

 sixteen grape-vines and endeavored to pass the 

 atmospheric electricity through the plant. Chem- 

 ical analysis of the plants at the end of the season 

 five months later showed only a slight difference 

 in the normal and treated plant's. 



Aloi found that atmospheric electricity works 

 favorably in the germination and growth of Lactuea 

 sativa, Zea Mays, Triticum sativum, Nicotiana 

 Tabacum, and Faba vulgaris. Cell employed static 

 electricity. He asserted positive results by charg- 

 ing a wire provided with numerous small points, 

 which were suspended over growing seedlings. 

 Freda experimented in a similar way with Penicil- 

 lium, but obtained negative results. 



Lemstrom obtained favorable results with static 

 electricity in a large number of cases, in which he 

 used a large Holtz machine. The wire meshes were 

 suspended over the plants which connected with 

 the positive pole, the negative pole being connected 

 with the ground. His experiments extended over 

 a period of years, during which time he employed 

 a larger number of plants than any of his prede- 

 cessors and, on the whole, his experiments are the 

 most trustworthy. He used a large variety of 

 plants, some of which were favorably and others 

 unfavorably stimulated. He demonstrated that 

 strong charges were unfavorable, and arrived at 

 the conclusion that electricity acts in an indirect 

 way, and that ozone is produced by electrical dis- 

 charges which have an influence on plants. 



Atmospheric electricity. 



Duhamel, in 1758, maintained that electricity 

 may be concerned with those remarkable atmos- 

 pheric changes which affect plants in so marked a 

 manner. Similar ideas were entertained by Mann 

 and Beccaria, who believed that after thunder- 

 storms plants of all kinds grew with remarkable 

 vigor. However, he attributed more marked effect 

 to the constant but feeble electric conditions of the 

 earth. Bertholon, in 1778, called attention to the 

 influence of meteors and lightning on the germina- 

 tion of seeds and the growth of plants. He attrib- 

 uted the failure of the hop crop in 1787 to the 

 comparatively small amount of lightning during 

 that year. In fact, it has been believed for many 

 years in Europe that there is some connection 

 between thunder-storms and the behavior of plants. 

 A common saying among the German peasants is 

 that if a thunder-storm occurs during blooming 



time buckwheat will not set its fruit. Some years 

 ago Lindley made measurements of plants during a 

 thunder-storm and found no particular differences 

 In their rate of growth, and Matthew thought to 

 have disproved the notions about buckwheat. 



Among farmers and others the idea has long 

 been held that milk sours very rapidly during thun- 

 der-storms. There appears to be some foundation 

 for this belief, although bacteriologists attempt to 

 account for it by the occurrence of the warm and 

 humid condition of the atmosphere which usually 

 precedes thunder-storms. Our experiments on the 

 influence of electricity on milk tend to show that 

 the farmer's idea is well founded, at least in many 

 instances, since a very slight charge of electricity 

 given to milk increases the number of bacteria 

 enormously in a very brief period of tme. 



Review of the early work. 



Taking into consideration the results of the 

 various experiments which are embodied in the 

 foregoing resume, there would appear, notwith- 

 standing the negative results, which, however, are 

 considerably less than the positive ones, to be some 

 reason for believing that electricity exerts an 

 influence on plant growth. Many of the experi- 

 ments giving positive results were notably crude, 

 especially the earlier ones, and even many of the 

 later ones are not detailed enough to allow of any 

 reliable conclusions being drawn. In the greater 

 majority of cases too few plants were used, faulty 

 methods were employed, the seeds were usually 

 sown in earth where no accurate means of deter- 

 mining the relative acceleration of germination 

 was possible. In the utter absence of measurements 

 of current strength and the growth of plants, the 

 results based on mere superficial comparisons were 

 of littJe more value than guesswork. In some 

 of the more recent experiments, however, compari- 

 sons have been made of the treated and untreated 

 plants by weighing, and in some instances chemical 

 analysis, a very uncertain method, was resorted 

 to. On the other hand, it should be borne in mind 

 that it is easy to repeat some individual experiment 

 that gives a positive result, and by introducing 

 some slight variation in the methods employed, or 

 modifying the strength of current, results of a 

 quite different nature may be secured. 



The most severe criticisms that can be brought 

 against the various experiments pertain to the lack 

 of sufficient data concerning the current strength 

 employed ; nor are there any data concerning the 

 resistance or electrical potential from which the 

 current strength might be calculated. The insuffi- 

 cient number of plants used and the lack of repe- 

 tition of various experiments under the same con- 

 ditions constitute serious objections. It would 

 appear that individual variation as a factor was 

 ignored in the majority of these experiments. 



Since there is a limited range of current which 

 accelerates growth, it is an easy matter to over- 

 step the range and obtain negative results. This 

 would seem to be the case in the very carefully 

 conducted experiments of Wollny. The same criti- 

 cism can be brought against Freda's experiments 



