De Lacepede, in 1779, found growth and germina tion invariably accelerated by the use of electricity. Marat, in 1782, experimented with lettuce and ob tained positive results. Bertholon subsequently repeated the experiments of Nollet and obtained similar results, and he moreover made many obser vations in regard to the effects of electricity on the ripening of fruit, color of flowers, and the like. He was the first to attempt to apply electricity in a practical way in the growth of crops, and he even went so far as to recommend it as a panacea for all diseases caused by insects and fungi. Achard, De Saussure and Gardini likewise reported beneficial results from the use of electricity.
Gardini stretched iron wires over his garden at Turin for the purpose of experimenting with atmos pheric electricity. After a short time the garden, which had been unusually prolific, began to fail, the plants became unfruitful and wilted. Ingen housz and Schwankhard, in 1785, made experiments with plants cultivated in Leyden jars filled with water, and obtained negative results. The experi ments were criticized by Duvarnier, who maintained that the methods employed were not satisfactory. Ingenhousz's negative results were confirmed by Sylvestre, Pacts, Van Troostwyck and Krayenhoff. Ingenhousz and von Breda repeated Gardini's experiments with overhead wires across a garden, but both failed in observing any effect whatsoever on the plants. In 1768, Carmoy sowed grains of wheat in electrified tin vessels and found germi nation and growth accelerated. Rouland secured negative results with cress seeds planted on plates of cork in electrified porcelain vessels filled with water. D'Ormoy electrified mustard and lettuce seed for several days in moist earth and found their germination always accelerated. Bertholon enclosed seeds of turnip, endive and spinach in tin-foil and kept them constantly electrified for some days, after which they were sown. He found germination accel erated. Vassalli, in 1788, obtained beneficial results from treatment, and so did de Rozieres, who experi mented with wheat, beans, rye, peas, radish, and others. De Rozieres maintained that not only was germination accelerated, but in all cases the electrified plants were larger, with longer roots and greener leaves. Hum boldt believed that electricity exerted considerable influence on plant growth. On the other hand, Sene bier was doubtful, while de Candolle was led to think by his experiments that elec tricity had very little effect on plants.
The various experi ments which were made with electricity up to this time were made with static elec tricity. With the dis covery of voltaric electricity, other methods of experimenting were employed.
From the year 1800, the suject of electricity and plant growth received little attention until 1844, when there was considerable interest manifested in the subject from the results of Forster's experi ments. He endeavored to utilize the atmospheric
electricity by stretching wires over a crop of barley, and found that growth was increased in a most extraordinary manner. In 1844, Ross made some experiments with galvanic currents which were described in the proceedings of the New York Farmers' Club. He planted a field of potatoes, at one end of which he buried a copper plate five feet in length and fourteen inches deep, connected with a wire to a zinc plate of the same size 200 feet away, at the opposite end of the row. According to Ross, potatoes grown on the treated row were two and one-half inches in diameter, while those grown on the untreated row in July were only one-half inch in diameter. Similar gal vanic culture experiments have been made by Sheppard, Helmert, Fitchner and SOhne, Tschinkel, Holdefleiss, Maercker, Wollny and others. Sheppard employed copper and zinc plates two feet long and nine inches wide. These were connected with wires and buried in the soil nine feet apart, and a num ber of seeds of different kinds were sown in be tween them. He found that many of the seeds germinated poorly, and some of the plants eventu ally died, although the electrically stimulated turnip plants showed a greater development than the check plants. Helmert found in some instances that growth was accelerated ; on the whole, how ever, he obtained negative results. Fitchner and Sane secured positive results with buckwheat, sum mer wheat, peas, and certain other crops. The gain was 18 to 127 per cent. Tschinkel obtained a con siderable acceleration in germination and growth.
The electrified plants, he asserted, were much more robust. He attributed the beneficial effects of elec tricity to the decomposition of certain salts in the soil. Holdefleiss found both growth and germination to be accelerated. Maercker experimented with sugar-beets, and his experiments showed no differ ences between the treated and the untreated plants either in the weight or percentage of sugar. Some experiments were made by Wollny on a more exten sive scale and in a very careful manner, with rye, beans, peas, potatoes, rape, beets and others, and in almost every instance he obtained negative results. Chemical analysis of the treated and untreated soil showed no difference in the amount of potash, ammonia, phosphoric acid and potassium nitrate, even when comparatively strong currents had been passed through it. Blondeau found that when seeds of peas, beans and wheat were treated one minute with a constant induction current, germination was hastened, and the electrified seed gave rise to stockier and greener plants. He also found that the fruit of the apple, pear and others ripened much earlier when subjected to electrical treatment.