Chapter 4

Among other insects, honey bees have been said to perforate flowers, but authentic instances are rare of their doing much damage, or even making holes. I have only recorded a single instance, and in this a honey bee was seen to perforate the fragile spurs of Impatiens. When searching for nectar they quite commonly use the perforations of other insects. Wasps and other allied insects also perforate for nectar. My only observations being a Vespa puncturing Cassandra calyculata, an Andrena (?) perforating the spurs of Aguilegia, and Adynerus foraminatus biting holes close to the base on the upper side of rhododendron flowers. The holes made by some of the wasp-like insects are often more or less circular and with clean-cut edges. The ravages committed by larvæ, beetles and other insects in devouring flowers, or parts of them, do not properly come under the head of perforations.

The question as to the cause of the handsome corollas of the trumpet creeper (Tecoma radicans) being so often split and torn has been accounted for in various ways in published notes on the subject. Humming birds and ants have been blamed, the humming birds being such constant visitors of these flowers that it really seemed as though they must be the authors of the mischief. I have often watched them when they appeared as though they were pecking at the blossoms, but careful examinations, both before and after their visits, always failed to show any trace of injury. Finally, on July 26, 1890, I was rewarded by seeing a number of Baltimore orioles vigorously pecking at and tearing open a lot of fresh blossoms, and this observation was afterward repeated. That the oriole should do this was not surprising, considering its known habits in relation to some other flowers. J.G. JACK.

[Mr. Jack adds a list of sixteen plants whose flowers he has seen punctured by the carpenter bee and seventeen others whose flowers were punctured by the humble bee. He names more than thirty other flowers which he has found perforated without having seen or identified the authors of the mischief.--ED.]--_Garden and Forest_.

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ELECTRICITY IN HORTICULTURE.

The influence of electricity upon vegetation has been the subject of numerous investigations. Some have been made to ascertain the effects of the electric current through the soil; others to ascertain the effect of the electric light upon growth through the air. Among the latter are those of Prof. L.H. Bailey of the Cornell University Agricultural Experiment Station. In Bulletin No. 30 of the Horticultural Department is given an account of experiments with the electric light upon the growth of certain vegetables, like endive, spinach, and radish; and upon certain flowers like the heliotrope, petunia, verbena primula, etc. The results are interesting and somewhat variable. The forcing house where the experiments were carried on was 20 × 60 ft., and was divided into two portions by a partition. In one of these the plants received light from the sun by day and were in darkness at night. In the other they received the sunlight and in addition had the benefit of an arc light the whole or a part of the night. The experiment lasted from January until April during two years, six weeks of the time the first year with a naked light and the balance of the time with the light protected by an ordinary white globe. It is not the purpose here to enter into any great details, but to give the general conclusions.

The effect of the naked light running all night was to hasten maturity, the nearer the plants being to the light the greater being the acceleration. The lettuce, spinach, etc., "ran to seed" in the "light" house long before similar plants in the dark. An examination of the spinach leaves with the microscope showed the same amount of starch in each, but in the electric light plants the grains were larger, had more distinct markings and gave a deeper color with iodine.

With lettuce it was found that the nearer the plants were to the light the worse the effect; and conversely those furthest away were the best developed. Cress and endive gave the same results. In the case of the latter, some of the plants were shaded from the light by an iron post, and these grew better and were larger than those exposed to its direct rays. The average weight of eight plants in full light was 49.6 grains, as opposed to an average of six plants in the shade of 93.8 grains. Radishes were strongly attracted to the light and moved toward it during the night. During the day they straightened up, but moved again toward the light at night. The plants nearest the lamp made a poor growth and were nearly dead at the end of six weeks. Averaging the weight of plant, of top and of tuber, it was found that those grown in the dark were heavier in every instance than those grown in the light; and the percentage of marketable tubers from the light-grown plants was twenty-seven, as opposed to seventy-eight in the dark. Chemical analyses showed the plants in the light to be more mature than those in the dark, although they were much smaller. Dwarf peas showed the same facts, those in full light being smaller than those in the dark. The former bloomed a week earlier than the latter, but the production of seed was less, being only about four-sevenths as great.

Further experiments were made by excluding the sun during the day and exposing the plants to the diffused electric light only. In all cases, with radishes, lettuce, peas, corn, and potatoes, the plants died in about four weeks. Only a little starch and no chlorophyl was found in the plants deprived of sunlight and only receiving the electric light. Thus the experiments with a naked light showed conclusively that "within range of an ordinary forcing house the naked arc light running continuously through the night is injurious to some plants." In no case did it prove profitable.

Experiments with the light inclosed in a white globe and running all night were different in their results. The effect was much less marked. Lettuce was decidedly better in the light house; radishes were thrifty but did not produce as much as in the dark house. A third series of experiments with the naked light running a part of the night only were also made. Radishes, peas, lettuce, and many flowers were experimented upon. The lettuce was greatly benefited by the light. "Three weeks after transplanting (Feb. 5)," we are told, "both varieties in the lighthouse were fully 50 per cent. in advance of those in the dark house in size, and the color and other characters of the plants were fully as good. The plants had received at this time 70½ hours of electric light. Just a month later the first heads were sold from the light house, but it was six weeks later when the first heads were sold from the dark house. In other words, the electric light plants were two weeks ahead of the others. This gain had been purchased by 161¾ hours of electric light, worth at current prices of street lighting about $7."

This experiment was repeated with the same results. In the second experiment the plants receiving eighty-four hours of electric light, costing $3.50, were ready for market ten days before the plants in the dark house. The influence of the light upon color of flowers was variable. With tulips the colors of the lighted plants were deeper and richer than the others, but they faded after four or five days. Verbenas were injured in every case, being of shorter growth and losing their flowers sooner than those in the dark house. "Scarlet, dark red, blue and pink flowers within three feet of the light soon turned to a grayish white." Chinese primulas seven feet from the light were unaffected, but those four feet away were changed. Lilac colors were bleached to pure white when the light struck them fairly. An elaborate series of tables of the effect of the light is given in the paper. The author believes it possible that the electric light may be used some day to pecuniary advantage in floricultural establishments.

These experiments naturally open up many questions. Those which will be of most importance to the practical man will be such as relate to the benefits to be derived from the use of the electric light. That electricity has a great effect upon vegetation can no longer be denied. What remains now is to ascertain how to use the force with the most economy and to the best advantage. If by its use early vegetables will be made earlier, bright flowers be made brighter, it will be a question of only a short time before it will come into general use. To the student of plant physiology there are also many questions of interest, but into these it is not the intention to enter. Prof. Bailey's general conclusions are, in part, as follows: "There are a few points which are clear: the electric light promotes assimilation, it often hastens growth and maturity, it is capable of producing natural flavors and colors in fruits, it often intensifies colors of flowers and sometimes increases the production of flowers. The experiments show that periods of darkness are not necessary to the growth and development of plants. There is every reason, therefore, to suppose that the electric light can be profitably used in the growing of plants. It is only necessary to overcome the difficulties, the chief of which are the injurious influences upon plants near the light, the too rapid hastening to maturity in some species, and in short the whole series of practical adjustments of conditions to individual circumstances. Thus far, to be sure, we have learned more of the injurious effects than of the beneficial ones, but this only means that we are acquiring definite facts concerning the whole influence of electric light upon vegetation; and in some cases, notably in our lettuce tests, the light has already been found to be a useful adjunct to forcing establishments.... It is highly probable that there are certain times in the life of the plant when the electric light will prove to be particularly helpful. Many experiments show that injury follows its use at that critical time when the planetlet is losing its support from the seed and is beginning to shift for itself, and other experiments show that good results follow from its later use.... On the whole, I am inclined toward Siemens' view that there is a future for electro-horticulture."

JOSEPH P. JAMES. Washington, Jan. 20, 1892.

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ELECTRICITY IN AGRICULTURE. By CLARENCE D. WARNER.

It is well known that currents of electricity exist in the atmosphere. Clouds are charged and discharged. There is a constant change of electricity from earth to air and from air to earth, the latter being the great reservoir for all electricity. Hills, mountain peaks, trees, high chimneys, spires, in fact all points elevated above the earth's surface assist greatly in charging and discharging the atmosphere. Again, if two iron rods are driven into the earth and connected by a copper wire with an electrometer in the circuit, the instrument is almost immediately affected, showing that currents of electricity are running through the ground. Now, what is the function of these atmospheric and ground electric currents? Many scientists are agreed that certain forms of precipitation are due to electrical action; but my observations have led me to believe conclusively that electricity is a potent factor in the economy of nature, and has more to do with the growth and development of plants than has hitherto been known. Davy succeeded in the decomposition of the alkalies, potash and soda, by means of electric currents. In our laboratories, water and ternary compounds are rapidly decomposed by the battery, and we may reasonably suppose that that which is effected in our laboratories by artificial means takes place in the great laboratory of nature on a grander and more extended scale.

Plant food is carried throughout the plant by means of the flow of sap; these currents circulate through all the rootlets and center, as it were, in the stalk, carrying their tiny burdens of various elements and depositing them in their proper places. That this phenomenon of circulation is due to electricity cannot be doubted. Most plants grow more rapidly during the night than in the day. May not the following be a reason for this?

We have already mentioned how electric currents pass from air to earth and _vice versa_; at night the plant is generally covered with dew and the plant itself becomes a good conductor, and, consequently, currents of electricity pass to each through this medium, and during the passage convert soil elements into plant food and stimulate the upward currents to gather up the dissolved elements and carry them to their proper places.

From the time electricity became a science, much research has been made to determine its effect, if any, upon plant growth. The earlier investigations gave in many cases contradictory results. Whether this was due to a lack of knowledge of the science on the part of the one performing the experiments, or some defect in the technical applications, we are not prepared to say; but this we do know, that such men as Jolabert, Nollet, Mainbray and other eminent physicists affirmed that electricity favored the germination of seeds and accelerated the growth of plants; while, on the other hand, Ingenhouse, Sylvestre and other savants denied the existence of this electric influence. The heated controversies and animated discussions attending the opposing theories stimulated more careful and thorough investigations, which establish beyond a doubt that electricity has a beneficial effect on vegetation. Sir Humphry Davy, Humboldt, Wollaston and Becquerel occupied themselves with the theoretical side of the question; but it was not till after 1845 that practical electroculture was undertaken. Williamson suggested the use of gigantic electrostatic machines, but the attempts were fruitless. The methods most generally adopted in experiments consisted of two metallic plates--one of copper and one of zinc--placed in the soil and connected by a wire. Sheppard employed the method in England in 1846 and Forster used the same in Scotland. In the year 1847 Hubeck in Germany surrounded a field with a network of wires. Sheppard's experiments showed that electricity increased the return from root crops, while grass perished near the electrodes, and plants developed without the use of electricity were inferior to those grown under its influence. Hubeck came to the conclusion that seeds germinated more rapidly and buckwheat gave larger returns; in all other cases the electric current produced no result. Professor Fife in England and Otto von Ende in Germany carried on experiments at the same time, but with negative results, and these scientists advised the complete abandonment of applying electricity to agriculture. After some years had elapsed Fichtner began a series of experiments in the same direction. He employed a battery, the two wires of which were placed in the soil parallel to each other. Between the wires were planted peas, grass and barley, and in every case the crop showed an increase of from thirteen to twenty-seven per cent. when compared with ordinary methods of cultivation.

Fischer, of Waldheim, believing atmospheric electricity to aid much in the growth and development of plants, made the following tests:

He placed metallic supports to the number of about sixty around each hectare (2.47 acres) of loam; these supports were provided at their summits with electrical accumulators in the form of crowns surmounted with teeth. These collectors were united by metallic connection. The result of this culture applied to cereals was to increase the crop by half.

The following experiment was also tried: Metallic plates sixty-five centimeters by forty centimeters were placed in the soil. These plates were alternately of zinc and copper and placed about thirty meters apart, connected two and two, by a wire. The result was to increase from twofold to fourfold the production of certain garden plants. Mr. Fischer says that it is evidently proved that electricity aids in the more complete breaking up of the soil constituents. Finally he says that plants thus treated mature more quickly, are almost always perfectly healthy, and are not affected with fungoid growth.

Later, N. Specnew, inspired by the results arrived at by his predecessors, was led to investigate the influence of electricity on plants in every stage of their development; the results of his experiments were most satisfactory and of practical interest. He began by submitting different seeds to the action of an electric current, and found that their development was rendered more rapid and complete. He experimented with the seeds of haricot beans, sunflowers, winter and spring rye. Two lots, of twelve groups of one hundred and twenty seeds each, were plunged into water until they swelled, and while wet the seeds were introduced into long glass cylinders, open at both ends. Copper disks were pressed against the seeds, the disks were connected with the poles of an induction coil, the current was kept on for one or two minutes and immediately afterward the seeds were sown. The temperature was kept from 45° to 50° Fahrenheit, and the experiments repeated four times. The following table shows the results:

Peas. Beans. Barley. Sunflowers. Days. Days. Days. Days. Electrified seeds developed in 2.5 3 2 8.5 Non-electrified seeds developed in 4 6 5 15

It was also observed that the plants coming from electrified seeds were better developed, their leaves were much larger and their color brighter than in those plants growing from non-electrified seeds. The current did not affect the yield.

At the Botanical Gardens at Kew, the following experiment was tried:

Large plates of zinc and copper (0.445 meter and 0.712 meter) were placed in the soil and connected by wires, so arranged that the current passed through the ground; the arrangement was really a battery of (zinc | earth | copper). This method was applied to pot herbs and flowering plants and also to the growing of garden produce; in the latter case the result was a large crop and the vegetables grown were of enormous size.

Extensive experiments in electroculture were also made at Pskov, Russia. Plots of earth were sown to rye, corn, oats, barley, peas, clover and flax; around these respective plots were placed insulating rods, on the top of which were crown-shaped collectors--the latter connected by means of wires. Atmospheric electricity was thus collected above the seeds, and the latter matured in a highly electrified atmosphere; the plots were submitted to identical conditions and the experiments were carried on for five years. The results showed a considerable increase in the yield of seed and straw, the ripening was more rapid and the barley ripened nearly two weeks earlier with electroculture. Potatoes grown by the latter method were seldom diseased, only to 5 per cent., against 10 to 40 per cent. by ordinary culture.

Grandeau, at the School of Forestry at Nancy, found by experiment that the electrical tension always existing between the upper air and soil stimulated growth. He found plants protected from the influence were less vigorous than those subject to it.

Macagno, also believing that the passage of electricity from air through the vine to earth would stimulate growth, selected a certain number of vines, all of the same variety and all in the same condition of health and development. Sixteen vines were submitted to experiment and sixteen were left to natural influences. In the ends of the vines under treatment, pointed platinum wires were inserted, to which were attached copper wires, leading to the tops of tall poles near the vines; at the base of these same vines other platinum wires were inserted and connected by copper wires with the soil. At the close of the experiment, which began April 15, and lasted till September 16, the wood, leaves and fruit of both sets of vines were submitted to careful analysis with the following results:

Without conductor. With conductor.

Moisture per cent. 78.21 79.84 Sugar. 16.86 18.41 Tartaric acid. 0.880 0.791 Bitartrate of potash. 0.180 0.186

Thus we see that the percentage of moisture and sugar is greater and the undesirable acid lower in those vines subject to electrical influences than in those left to natural conditions. There are also experiments which prove the beneficial effects of electricity on vines attacked by phylloxera.

The following experiments were made at this station: Several plots were prepared in the greenhouse, all of which had the same kind of soil and were subjected to like influences and conditions. Frames in the form of a parallelogram, about three feet by two feet, were put together; across the narrow way were run copper wires in series of from four to nine strands, each series separated by a space about four inches wide, and the strands by a space of one-half inch. These frames were buried in the soil of the plot at a little depth, so that the roots of the garden plants set would come in contact with the wires, the supposition being that the currents of electricity passing along the wires would decompose into its constituents the plant food in the vicinity of the roots and more readily prepare it for the plants. Two electric gardens were thus prepared and each furnished with two common battery cells, so arranged as to allow continuous currents to pass through each series of wires. Near each electric garden was a plot prepared in the same manner, save the electrical apparatus. We will call the two gardens A and B.

The place chosen for the experiments was in a part of the greenhouse which is given up largely to the raising of lettuce, and the gardens were located where much trouble from mildew had been experienced. The reason for this choice of location was to notice, if any, the effect of electricity upon mildew, this disease being, as it is well known, a source of much trouble to those who desire to grow early lettuce. The soil was carefully prepared, the material taken from a pile of loam commonly used in the plant house.

Garden A was located where mildew had been the most detrimental; the experiments began the first of January and closed the first of April. For the garden, fifteen lettuce plants of the head variety were selected, all of the same size and of the same degree of vitality, as nearly as could be determined; the plants were set directly over the wires, so that the roots were in contact with the latter; the plants were well watered and cared for as in ordinary culture, and the fluid in the battery cells was renewed from time to time, that the current of electricity might not become too feeble. At the close of the experiments the following results were noted:

Five plants died from mildew, the others were well developed and the heads large. The largest heads were over the greatest number of wires and nearest the electrodes. It was further noticed that the healthiest and largest plants, as soon as the current became feeble or ceased altogether, began to be affected with mildew. On examining the roots of the plants it was found that they had grown about the wires as if there they found the greatest amount of nourishment; the roots were healthy and in no way appeared to have been injured by the current, but, rather, much benefited by the electrical influences.