1271. Fish forms a powerful manure, in whatever state it is applied; but it cannot be used too fresh, though the quantity should be limited. A. Young records an experiment, in which herrings spread over a field, and ploughed in for wheat, produced so rank a crop, that it was entirely laid before harvest. The refuse pilchards in Cornwall are used throughout the country as a manure, with excellent effects. They are usually mixed with sand or soil, and sometimes with sea weed, to prevent them from raising too luxuriant a crop. The effects are perceived for several years. In the fens of Lincolnshire, Cambridgeshire, and Norfolk, the little fishes called sticklebacks are caught in the shallow waters in such quantities, that they form a great article of manure in the land bordering on the fens. It is easy to explain the operation of fish as a manure. The skin is principally gelatine, which, from its slight state of cohesion, is readily soluble in water; fat or oil is always found in fishes, either under the skin or in some of the viscera; and their fibrous matter contains all the essential elements of vegetable substances. In fact, the whole body consists of those substances which constitute the food of plants; prone to decompose, and rapidly changing into those compounds which are most easily absorbed and assimilated by plants.