Of late years growers of Ferns, Cucumbers, Tomatoes, etc, have been much concerned as to the best means of rendering their plants immune from attacks of eelworm and other pests. The soil has been regarded as the seat of all the mischief, and various nostrums have been boomed as infallible remedies against all the diseases that attack market crops. At first some of these remedies appeared to check the disease, but after a time the trouble was as rampant as ever. The only things that have not been tried are cultivation and common sense. Soils have been brought into cucumber houses at great expense, and have been closed with rich organic and chemical manures to such an extent that acidity becomes one of the predominant features. Under a high temperature, 85° to 95° F. and more, and an excessively humid atmosphere, trillions of bacteria are brought into being. Bearing in mind what has been said at p. 127 about nitrate-forming bacteria growing lazy owing to having too much nitrogenous food at their disposal, it is not to be wondered at that they fail to perform those beneficial duties which they carry out in a soil containing only a reasonable amount of organic material. Other bacteria, no doubt, then come into play and doubtless devour the lazy ones, and bring about such a condition of the soil that other troubles, like eelworms, arise and play havoc with the roots of plants.

This being the case, the simplest plan would appear to be to keep the soil from becoming acid by giving less rich food and more lime - the latter not only to counteract acidity, but also to induce the beneficent bacteria to carry on their work. In addition to this, plenty of fresh air must be admitted when possible, according to the state of the weather, because the bacteria must have fresh supplies of oxygen to encourage their activity. Many plant houses are so poorly ventilated that they become "stuffy" with the stale atmosphere in them.