No kind of animal manure should be used in a garden (except for making hotbeds) till it is thoroughly decayed and all fermentation is gone off; as while it is in process of decay the gases it evolves are decidedly hurtful to plants. Those manures which abound in nitrogen, such as stable manure and the dung of birds, are the strongest and most dangerous; as if used incautiously they will blacken and shrivel up the leaves of the plants to which they are applied. Guano and pigeon's dung are very much alike in their properties, and both are of an extremely caustic nature; so that they should only be used in very small quantities, or be very much diluted. One ounce of guano to a gallon of water is a common proportion; or the guano may be mixed with six or seven times its own bulk of loam, peat, or charcoal, and dug into the ground before the crops are sown: if applied afterwards as a top dressing, it should be either in wet weather, or the soil should be well watered. Charcoal is very efficacious in some cases, but it appears variable in its action; as sometimes it produces scarcely any effect. Nitrate of soda and saltpetre act principally by supplying a particular kind of earth to plants that are in want of it, and of course will not suit all plants; but they are also of service in keeping the earth moist, and this, when not carried to an excess, is always useful. When it is wished to keep plants constantly in a growing state, the soil should be rendered rich, and the plants should also be watered frequently, so as never to suffer the soil to become quite dry; equal care being taken to keep it free from stagnant water, which would rot the roots. When, however, the plant is to be hardened, to stay out the winter, it should be kept as dry as possible, and no manure should be applied for some time previously to the cold weather setting in. Nothing is less generally understood than the use of manures. They are in fact food; and should not be given to plants in excess, any more than children should be crammed with food. Starving and repletion should both be carefully avoided; and the great art of the cultivator is shown in supplying plants with food only when they need it. Too much water will sometimes produce leaves and stems instead of fruit and flowers; and shoots of great luxuriance very frequently do not ripen, and are killed by the first frost.