Is it the educt of organic or inorganic disease? or is it the product of external circumstances? Is it a disease in the sap of the plant, brought up and through its organism, and left as an excrement on the stomata, and its constituent elements, under the action of atmospheric chemical changes, producing the fungi? or is it the product of certain external compositions forming vegetable lite, and when so formed falls upon the healthy foliage of certain varieties of plants and destroys them? Some are of opinion that this fungi floats in the atmosphere, is inhaled through the leaves, and carried into and through the plant organism, and thrown out again in increased multitudes on the upper surface of the leaves; but how this is possible, I for one can not comprehend. If there is any law in vegetable physiology that warrants this statement, we hope the "doctors" will be kind enough to point it out. One thing we do know from experiment, that placing lumps of caustic lime at intervals through the house has prevented entirely any of its appearance throughout the whole season.

It may be contended that the only action of this lime was that of absorbing carbonic acid; be that as it may, with me it is the chloride of lime for our vegetable sick-chamber.

Whether the seeming purifying action of lime on the atmosphere is the prevention, or dissipates the elements which may combine to form vegetable life in the form we call fungi, or whether the plant throws off some vegetable mucus which may stop and clog up its stomata, through some uncongenial compound in the food by which it exists, and that the lime has some peculiar property of absorbing or decomposing this exhalation, is what we should much like to know. It is of no avail to those who have to contend with this pest, to know that doctors A, B, and C know all about it; we want to know how they know. Neither is it much consolation to the inquiring mind to know that a preventive is at hand. He may feel thankful for his crop being saved; but this does not explain cause and effect. If you are growing a grape-vine in pot or tub, (forcing,) and saturate it well at the roots with ice-water, in thirty-six hours you will find it covered with mildew. You can do the same with any vine growing in a border in the house. Cold water will mildew roses and many other plants in the same way. Cold currents of air act nearly in the same manner, unless the vines are from their first commencement of growth perfectly inured.

We hope the "doctors" will send up some good ideas to the "Battery" at 25 Park Row, New York, and while they are analyzing, the gardeners say they will be thinking.

[Yes, quandaries do indeed flash across an editor's mind as he sits in his sanctum, which make it any thing but "nice and cosy." A good editor, however, contrives to work them up into, good ammunition with which he keeps his "Battery" well charged; but unless he has ability and knowledge of his own, he is just as apt to fire blank cartridge as round-shot. Fox Meadow is up to a good suggestion. By all means send us your ideas, and don't trouble yourselves too much about good writing: we'll take care of that; we are probably better judges of that kind of thing than you are. Now won't somebody pitch into mildew in the right place? We know that lime, as mentioned by Fox Meadow, is a good preventive, as we have tried it for years: it also has a good effect in keeping down red spider. Mildew is becoming a more formidable enemy every year, and our true policy is to fight it before it becomes firmly intrenched. - Ed].