At the other end of the scale, almost exactly opposite in every particular, are those soils in which clay predominates. Soils of this type are cold, they dry out very slowly, and as a result it is late before they can be fitted for planting. In dry seasons, because of their water-holding capacity, they are greatly to be preferred, and plants growing on them are less liable to suffer from drought. Clay soils, because of their stickiness, are very difficult to work, and although they may be well supplied with plant food, it is sometimes unavailable because of the sticky, tenacious character of the clay which does not provide a good medium in which the roots may ramify in search of food. Peat soils and muck lands are made up largely of decayed organic matter. They are usually deficient in minerals, but by correct management can be made to produce good crops of certain kinds of vegetables. Enormous quantities of celery and onions are successfully grown on muck soils. The kind of soil most desired by the gardener is the happy medium that is called loam. This consists of a mixture of clay and sand in nearly equal proportions, combined with a considerable quantity of decayed organic matter. Such soils are fertile, easy to work, retentive of moisture, but sufficiently porous so that the moisture is not retained in excess. Air can penetrate such soils, a prime necessity for healthy root growth, and also necessary for the existence of bacteria which do so much in making inert plant foods soluble and available for the use of plants. The extreme types of soil previously mentioned can be greatly improved by judicious treatment. It will be remembered that one of the great drawbacks to sandy soils was the readiness with which they lose their moisture. The proper treatment for this type is to add organic matter. This decays and forms humus, which binds the coarse particles together to a certain extent and increases the absorbtive and retentive properties of the soil. This organic matter is best applied in the form of decayed, or partially decayed, barn-yard or stable manure. If manure is not available a good substitute can be found in leaves. These may be gathered in the fall and piled in a heap to decay. Very little decomposition will take place during the winter months in the Northern states, and for this reason leaves that have been piled in heaps for twelve months or more are to be preferred. Decay may be hastened by forking over the leaves two or three times during the summer. Although decayed leaves are better than fresh ones for mixing in with the soil, fresh leaves are better than none at all. The owners of city gardens frequently neglect an opportunity of adding humus to their soil when they allow the leaves of street trees to be burned or carted away. The city street-cleaning department is usually only too glad to be relieved of this duty.