we are on somewhat difficult ground. But it can probably be accounted for in two ways. In the first place the positive current passing from the points of the wire net to the earth causes the production of ozone and nitric compounds which are beneficial to the plant. In the second place the negative electricity passing up from the earth to the points of the net tends to draw up with it through the plant the sap from the root, and thus the increased circulation of the juices gives increased energy of growth. Of course, in the application of electricity, as in the use of all good things, there must be moderation, and individual plants require individual treatment as to the exact strength that is best for them.

But in all matters such as this the mundane and first question asked by a practical farmer is "Will it pay?" Or will the cost of the apparatus swamp the increased profits? For the commercial aspect is perforce the one that appeals to him most. To this inquiry Professor Lemstrom asserts that he can give a most satisfactory answer -it will pay. Thus take the case of wheat, for example, and suppose a hectare (24.7 acres) is put under electroculture. The initial cost of setting up the apparatus he estimates at about £108, the annual upkeep at £23. Now, reckoning wheat as giving 34 bushels to the acre, an increase of 45 per cent. due to the electric current will give an increase of 383 bushels for the field, and 383 bushels at 3s. 6d. give £67 profit. Deducting for the upkeep of the machine we have a net profit of £44 for that one field, or more than four-tenths of the whole cost realized in the first year. The larger the area worked the greater the profit, since the cost of working does not increase in the same ratio.

It is interesting to learn that Professor Lemstrom was led to take up

this line of research through his voyages to the Polar regions. He saw there that the plants showed a rapid development far surpassing that of plants in more southern climes; he saw, too, great differences in the size of wood rings in different years, and he noted the pointed needle leaves of the pines and the spikey beards of the corn. Then, with the keen eye of the man of science, he realized that the largest rings in the wood and the greatest harvest occurred in the years when there were more sunspots, when the aurora played more vividly, when, in fact, the air was largely charged with the electric fluid, and he comprehended the reason of the spikes, leaves, and beards. And from this vantage ground he was led through years of study to the conclusion that electricity must be numbered among the principal factors in plant life, a factor that, up to the present, has been practically overlooked, but which, nevertheless, plays a most important, though subtle, part in it.

Other workers, both French and English, confirm the above, and in some respects amplify it. Thus Dr. Cook found that if he electrified seeds he not only produced more successful plants from them, but a greater percentage germinated. It is as though life in some of them was flickering but faintly, and would have gone out altogether had not the electric stimulus fanned it into flame.

French men of science working at electroculture have been largely devoting their energies to trying to utilize the electricity of the atmosphere. If this could be done a practically unlimited source at nominal expense could be obtained. And their experiments show that the idea is feasible. For instance, by setting up a geomagnetifère-practically a lightning conductor -in the centre of a field, and connecting it with a network of wires running

through the soil of the field, an increase of 50 per cent. was secured in a potato crop, while an even greater percentage of improvement showed in tomatoes, peas, and other plants experimented upon. In fact, we may conclude that on all counts electricity stimulates growth and development in the plant world, and that electroculture has an undoubted future before it. But electricity provides yet another means of jogging Nature's arm, though in this case it is not the direct action of the force, but its power as an illuminant, on which is based a second important and recent development in plant-growing. As long ago as 1881 Sir W. Siemens experimented upon plants with electric light, but the light was costly, and the matter fell through for some years. But at the end of last century the question was taken up again in both America and France, and most interesting possibilities were disclosed. The American experiments simply arranged for a number of plants to be kept in cool glasshouses and the electric light to be turned on for some hours, brilliantly illuminating them when night fell, and thus shortening the time of darkness, but not abolishing it altogether. In neighboring cool glasshouses similar plants were grown under normal conditions of day and night. The result was that the plants with the longer period of light throve better and developed earlier than the others. Lettuces, radishes, beet, and spinach all improved, but the lettuces in particular. A few plants, such as cauliflowers, like some people who cannot do with their hours of sleep curtailed, did not come up to the standard, but they were in a small minority. Violets, daisies, and other flowers bloomed more freely and better, though they, in common with other plants are apt to feel the reaction and be more exhausted than the normal, just as a man feels additional fatigue

after a spurt of hard work. Still, this eventual exhaustion of a plant is a matter of minor consideration to a florist if he can get his blooms earlier on the market, and larger and more richly colored into the bargain. And therein comes another peculiarity and virtue of the electric light stimulus; it leads to increased brilliancy of color both as to the green of the leaves and the hue of the flowers, and this discovery suggests another line of development in plant-growing which has yet to be worked out.

The French experimenters were not satisfied with treating the plants under consideration to a few hours of electric lighting. They went the whole length and left them no rest. Even the change to sunlight was denied them. Day and night unceasingly they were exposed to the full glare of the electric arc. In fact, one may compare the American treatment to the case of a man who takes alcohol occasionally in moderation, the French treatment to a man who uses alcohol as his sole nourishment, for the results are analogous. In the American method and the moderate man the stimulant is effective and not evil; in the French method and the intemperate man the outcome is stunting, disfigurement, and degradation. After some six months' continuous subjecting to the light a common pea had a fat, twisted stem with tiny, undeveloped leaves, and other plants showed similar abortions. The green color was, however, emphasized. Everything was intensely green, thus carrying the heightening of hues a stage further from the brightness observed under the moderate electric light treatment. All this, too, is comparable to the brilliance of tints under an Arctic summer, when the days are very long and the nights are very short. And this possibility of a development of intensity of color is a line of research

that might easily be taken up by many well-to-do amateurs who, in these days, have electrically lighted conservatories in their houses.

A third development in recent plantgrowing is known as radioculture, and is curious and somewhat sensational. It consists in growing plants in differently colored glasshouses; that is to say, instead of the glass being clear white as is usual in greenhouses, in one case it is red, in another green, and in yet another it is blue, care being taken that in every case the color of the glass is absolutely pure. A series of experiments on these lines was first conducted by the eminent French astronomer, M. Camille Flammarion, and they proved very suggestive. He took a number of the seedlings of the Sensitive Plant (Mimosa pudica) (choosing this plant because of its peculiar sensitiveness) and divided them into four similar groups; one group he placed in an ordinary greenhouse, a second he placed in a blue house, a third in a green house, and a fourth in a red house. Then giving to each the same care and attention, and arranging that the intensity of the light should be the same in each case, he awaited eventualities. At the end of a few months he made an exact comparison between them, and found striking differences. In the blue house the little plants were practically just as he had put them in; they were alive and well, but they had not grown or produced new foliage or development in any way. Like the Sleeping Beauty in her castle they had seemingly fallen asleep on the day they went into blueness, and remained unchanged as in a trance. In the green glasshouse the seedlings had certainly shown considerable energy in growing, more so than their contemporaries in the ordinary glasshouse, but, on the other hand, their growth was not really satisfactory, for, though tall, they were in

the red house there were wonderful happenings. The seedlings had become positive giants, and well-nourished and well-developed ones, too. They were fifteen times as big as their sleeping fellows in the blue house, and four times as big as the normal control plants. Moreover, they had produced little round flower balls, which none of the others had even attempted; but, more remarkable still, their sensitiveness had increased to an amazing extent. It is well known that if the sensitive plant is shaken or touched all its leaves immediately fold up and their stalks droop, and it is only by degrees and slowly that it recovers from the shock. Now in the red light the plants had become hypersensitive; in fact, one might almost say quite neurotic; at the slightest breath of air their leaves shrank together and hurriedly drooped. Obviously the red light had in every way stimulated their development to an abnormal extent. They were in the greatest possible contrast to the "blue" mimosas, for these had absolutely no feeling at all, and no amount of touching or jarring could prevail on them to respond. Indeed, in every way their life had been deadened.

Encouraged by these results, other plants were afterwards experimented upon, such as oaks, lettuces, and crassulas, and many additional points of interest brought out. Thus, while little oak trees (they were several years old) produced but few leaves in the blue house, their leaves did not fall in the autumn as did the numerous welldeveloped leaves in the red house, where branches as well as foliage had been added during the summer of experiment. Blue light, therefore, retards the processes of decay as well as those of development. In the matter of brilliant colorings, both as to leaves and flowers, it was found that colored light

of any sort tended to its elimination; pure white light is necessary for the production of these tints in plants.

Radioculture has not yet been taken up to any extent for practical purposes by florists and gardeners, who are hanging back for further assurance of its value. But it is obvious that there are definite possibilities in it. One would imagine that a red house would become in time an indispensable adjunct to a florist's garden for forcing purposes, and in any event such a powerful stimulant to plant life as red light cannot be overlooked long. A blue greenhouse suggests itself as a place where plants, perhaps at the height of their beauty, could be kept for a time, at any rate, in a quiescent condition, to re-emerge on special occasions to the advantage of the florist and the delight of his customers, for delay of decay may be as valuable an asset in practical gardening as premature development.

When we come to look into the fourth line of development marked out by this recent research into the factors that affect plant life, we find that it is altogether different to the three already described. It trenches on a field of knowledge in which, in the last few years, immense explorations have been made the great field of bacteriology-and though, in some respects, it has met with practical difficulties that have checked its progress for the moment, yet it holds within its confines great potentialities. It maintains that it is possible to improve certain crops under certain conditions by inoculating the soil or the seeds with suitable preparations of bacteria. Now it is well known that leguminous crops, such as peas, beans, and so forth, valuable in themselves, have a further special value in that instead of impoverishing the soil in which they grow they absolutely tend to enrich it. All other crops but these take nitrogenous

matter out of the ground in their growth, and hence subsequent manuring with expensive nitrogenous manure is essential if the soil is to be kept up to the standard quality. Why leguminous crops acted differently was a mystery until Professor Hellriegel, of Germany, came forward with an explanation. He showed that the curious little nodules which usually plentifully besprinkle the roots of peas, beans, and so forth, are really the homes of colonies of bacteria, and these bacteria can do what no ordinary green plants can do: they can absorb raw nitrogen from the air and work it up into various complex compounds necessary for plant life. These compounds they pass on to their hosts, so that it is clear that they richly pay for the shelter that is afforded them in the root nodules. But if by any chance the roots of leguminous plants are badly, or not at all, furnished with the nodules, then their crops are no kinder to the soil than their neighbors', and despoil the earth instead of enriching it. Therefore it was suggested by Dr. Nobbe, of Saxony, that where we find poor leguminous crops in all probability the reason is because the soil is poor in the bacteria with which they desire an alliance. To test his point he took some soil in which plants with many root nodules had been growing, and which soil he inferred to be rich in these bacteria, and he spread it very thinly over poor soil where similar crops had been a failure. Rain intermingled the two soils, and then he resowed leguminous seeds. The results fully justified his expectationsthe new crop was far superior to the previous ones, and the nodules-the bacterial homes-were far more numerous on the roots. Thus encouraged, he prepared cultures of these bacteria, whereby, in the form of a powder, he was able to compress myriads of these organisms into a bottle, for obviously

the actual cartage of soil, possibly over long distances, would be a very serious obstacle to any practical utilization of his discovery. This bacterial powder he called Nitragin, and it could be used in two ways. In the first, known as soil inoculation, it was moistened with water and poured over loose soil, which soil was then spread over the desired field and deeply harrowed in, and the seed then sown. In the second, known as seed inoculation, the moistened Nitragin is sprinkled directly over the seeds, which are rolled in sand or loam and sown at once. Here, directly they germinate, they find the desirable partner, the bacterium, ready to take up its abode in the root tissues, greatly to the benefit of both. The second system seems in practice to prove the better of the two.

The question was taken up in Canada at the State Experimental Farm, and many experiments made in very poor soil, with the result that the Nitragin-treated seeds in every case produced much finer crops than those which were not inoculated. Peas, beans, clovers, all confirmed this verdict, so the value of Dr. Nobbe's inferences is established. The fact that Nitragin in itself still requires further research to render it a commercial success-it will not keep long, and is too sensitive to its environment in the matter of heat and light-in no way detracts from the great principles involved. We know now that in certain respects there is interdependence between plants and bacteria, just as between animals and bacteria, and that it is possible to inoculate one as the other and influence the after career. We have discovered, too, that we can manipulate these bacteria and introduce them to the plants as we wish. And this knowledge opens up a new country where the vista is indeed wide and the limits to which are beyond our ken. Why should one set of plants

Under

The last development of modern plant-growing that it is proposed to treat of here is also the most recent, and it, in its turn, differs from the preceding ones we have discussed. It consists in forcing plants by the use of anæsthetics, a truly remarkable procedure first put forward by Dr. Johannsen, of Copenhagen, at the beginning of this century, and since then amplified by other botanists, particularly French ones. The plants to be treated are placed in a very dry state on a bed of dry sand in a box capable of being hermetically sealed. the cover of the box is suspended a small vessel into which ether is poured through a hole at the top, which hole is immediately closed. As the ether evaporates the heavy vapor descends to the bottom of the box and envelops the plants lying there. After some forty-eight hours the plants are taken out and placed in a cool house and treated as usual. The result is that the buds and flowers at once begin to sprout far more rapidly than those of unanæsthetized plants do, and are finer than usual. Thus, after being etherized, lilacs had abundant flowers and leaves, and were quite decorative plants in thirteen days, while lilacs under normal treatment only had a few flowers and no leaves at all at the end of seventeen days. Azaleas, lilies-ofthe-valley, deutzias, spirea, and other plants experimented on all showed wonderful powers of early development after being under the influence of ether. One of the leading German horticulturists, hearing of Dr. Johannsen's experiment, went specially to Denmark to see them, and his verdict