As this subject lies at the root of all good culture, you should have it fully discussed; every member should state the result of his practice and observation, and bring all the virtues of the different fertilizing materials to light. I will contribute my mite with some data. We should cultivate enlarged views; look over the garden fence upon the farm, and consider the value of the products. My own soul was once so small as to bury my brains in a flower-pot, and to think that a garden with a few glass structures was the universe; but now I see what a big place the world is. It is generally conceded by cultivators, that barn-yard manure is the best manure for common use; and as it is the droppings of several species of animals, together with straw, I think it better than that of any one specie, when applied to clayey soils and heavy loams in its long fresh state. It warms them, renders them more porous, and allows the roots of rapid-growing plants to enter them more freely. Indian corn, potatoes, melons, squashes, &.C., seem to do best upon heavy soils with fresh barn-yard manure; but for sandy and light soils it is best when well rotted, and in that state has a more immediate effect on crops in general.

For potting plants it should be almost a mould, and be mixed many months with the soil before being used. Ligneous manures I think must be most beneficial to trees and other woody plants, although seldom ever applied to them. Leaf mould is almost indispensable in pot culture, and the mould at the bottom of the wood pile is better; wood ashes leached, are used extensively upon sandy soils, produce good crops, and solidify such soils; waste charcoal is valuable in pot culture, but too expensive for general use; sawdust is all converted into manure around the city of Edinburgh, Scotland, by bedding cows and horses with it. Tan-bark is also there converted into manures by composting it with other materials, and nurserymen grow the hardier rhododendrons and azaleas in beds outdoors, made up with two thirds of decayed tan-bark and one-third garden loam. Salt at manure hastens vegetation, and give earlier maturation to plants than any other kind of manure. I have used night soil fresh from the walls of this city, upon acres; and for onions, beets, radishes, turnips, and carrots, I have never found anything to equal it for early and heavy crops. Poudrette has a similar offset, bat these rich matters make cabbage "clubfooted," and do not suit potatoes.

The low meadows around Edinburgh, into which the sewers of the city empty, yield the greatest crop of grass to be found; they are divided into lots of three and four acres by ditches which lead the liquid manure aroond them, and are flooded with it at pleasure; they are let yearly at auction to dairy-men. The grasses are fit to cut by the time that grasses elsewhere begin to grow in the spring; they give seren cuttings knee high, and so heavy that the scythe can hardly carry the swath through. The market gardeners of Leith surpass all their contemporaries more inland in the production of early and fine vegetables by the use of sea-weed they gather off the beach after a high tide or storm. Upon the flat meadows of Long Island Sound, between Harlem and Throgg's Keck, the grass, after being flooded by a "spring tide," grows up at a wonderful rate; and asparagus of the finest quality springs up spontaneously all over these. Country people empty the brine of their meat and fish barrels in spring upon their asparagus beds, which is the only manure they get, and they yield plentiful crops.

I have used both salt, lime, and urine around the base of peach and plum trees for the cut-worm, which always keeps them off and invigorates the trees.

Walter Elder #1

The questions to be answered in the discussion of this subject, so far as I understand it, are: What is Mildew? Whence does it come ; Where is it found? And how can we guard against it 1.

1st There is a diversity of opinions as to what mildew is; some assert that it is a parasitic fungus; a genus of plants of many species, which bear fruit and propagate themselves by seeds. And this answers the first two questions.

3d. Where is it found? It is found upon nearly all kinds of decomposing bodies, requiring a certain degree of moisture for its workings, either in the air or in the bodies upon which it is found. Ripening grains that have been lodged by heavy rains, and remain long wet, and when shocked and stacked, if not fully dry. Wall-papers produce it when the walls are long wet and the rooms dark; our wearing apparel and eatables, kept long in damp closets and cellars. What we call "fire-fang," in dung-heaps, is mildew; it is upon grape-vines, roses, peach-trees, Ac., when growing in forcing-houses; turnips, cabbages, gooseberry-bushes, etc., when growing upon a dry soil, and in a dry atmosphere, and exposed to tho sun. It can not exist upon a dry, light, and airy surface, nor in water. Wherever yon find darkness, moisture, and exclusion of fresh air. there yon will find mildew, and decomposition going on; upon whatever living plants it is found, they are suffering from a reaction in their growths, and are in a state of decomposition. And mildew is the sign which is first observed upon the leaves, young shoots, and fruits, and if unchecked will soon destroy the plants altogether.

And it is only when plants are growing upon a soil and in an atmosphere unsuitable to their natures, that they are affected with mildew. The exotic grape growing out-doors in our Middle States, and the peach-tree growing out-doors in the north of Europe, are affected with mildew, the climates being unfavorable to them. The exotic grape Is free of it, growing upon the hill-sides of France; the peach-tree generally, growing in our open fields in the Southern States; the rose in the open gardens; as heat, dryness, and pure air are their especial requisites; but when growing in forcing houses, stimulated with rich manures, artificial heat, a confined air, and an excess of moisture, their vitality is overstretched and weakened; a slight reaction throws them into a state of consumption or decomposition; hence the cause of mildew upon them. Turnips, cabbages, gooseberry-bushes, etc., are free of It when growing in moist soils and cool atmospheres.

4th. How can we guard against it I This, in a horticultural view, is the most important point; but as it has baffled all the most skilful cultivators the world ever saw, we can not expect to be always free of it in our forcing-houses. We should grow all our plants as nearly in accordance with nature as possible: but how can gardeners supply all the requisites of many different genera and species, growing promiscuously in a glass-house? Where the exotic grapevine, peach, and nectarine trees are only grown, the same remedy and preventive will suit them all. Lime and sulphur will greatly arrest the evil, and save the plants and their fruit from ruin; clear light, pure air, cleanliness, a uniform temperature, the wall frequently whitewashed with hot lime, fresh slacked lime frequently dusted over the floor, will tend greatly to prevent the appearance of mildew. The new-fashioned glass houses, with stationary roots and large glass, are far superior to those with deep and heavy rafters and small glass, as they give more light and less shade; the manner of ventilation is also better.

The whitewash upon the glass in summer should be very thin, so as to let the light be clear without scorching; thick whitewash is too cloudy in dull weather, which greatly increases the spread or propagation of mildew; darkness, too, is very hurtful to all kinds of plants when under a high temperature, and might cause a reaction in their growths, as sudden changes of temperature often do. Another cause of mildew is the crowding of plants too closely in the bouses, which makes too much shade, and retards the free circulation of fresh air among them; and who knows but when the grapery is long close shut up in winter, the seeds of mildew may be sown, and not appear visible until heat and moisture are applied in spring? and it is for this reason that I think that every glass structure for growing plants should have a chimney, like a dwelling house chimney, and always kept open, both to admit fresh air and to allow impure air in the house to escape. Any person may be convinced of the importance of this, by going through a dwelling-house that has been long shut up; he perceives the difference of air in rooms with open chimneys and those which have not.

I think that mildew is a messenger sent to us from heaven to tell us of the approach of evil - to remind us of our duty, and to caution us against imprudence in overdoing our work. In conclusion, I say, guarding against sudden changes in the temperature of the houses, a strict observance of cleanliness, and a rigid adherence to the scientific principles of ventilation so ably explained to us lately by William Saunders, in his essay upon that subject, will do muck to prevent the ruinous effects of mildew in forcing-houses.

Some additional remarks were offered, when it was proposed to continue the discussion of the subject at the next meeting; and members are requested to submit specimens of the more prominent forms of fungi which cause mildew, as well as reliable authorities on the subject.

The meeting, having adopted this proposition, adjourned.