=Purity= (of seed): seeds are pure when they contain only one kind of seed and no foreign matter. =Ration=: a fixed daily allowance of food for an animal. =Raupenleim=: a patented sticky substance used to catch the cankerworm. =Resistant=: a plant is resistant to disease when it can ward off attacks of the disease; for example, some varieties of the grape are resistant to the phylloxera. =Rotation= (of crops): a well-arranged succession of different crops on the same land. =Scion=: a shoot, sprout, or branch taken to graft or bud upon another plant. =Seed bed=: the layer of earth in which seeds are sown. =Seed selection=: the careful selection of seed from particular plants with the object of keeping or increasing some desirable quality. =Seedling=: a young plant just from the seed. =Sepal=: one of the leaves in the calyx. =Set=: a young plant for propagation. =Silo=: a house or pit for packing away green food for winter use so as to exclude air and moisture. =Sire=: father. =Smut=: a disease of plants, particularly of cereals, which causes the plant or some part of it to become a powdery mass. =Spike=: a lengthened flower cluster with stalkless flowers. =Spiracle=: an air opening in the body of an insect. =Spore=: a small body formed by a fungus to reproduce the fungus. It serves the same use as seeds do for flowering plants. =Spray=: to apply a liquid in the form of a very fine mist by the aid of a spraying pump for the purpose of killing fungi or insects. =Stamen=: the part of the flower that bears the pollen. =Stamina=: endurance. =Sterilize=: to destroy all the germs or spores in or on anything. Sterilizing is often done by heat or chemicals. =Stigma=: the part of the pistil that receives the pollen. =Stock=: the stem or main part of a tree or plant. In grafting or budding the scion is inserted upon the stock. =Stover=: as used in this book the word means the dry stalks of corn from which the ears have been removed. =Subsoil=: the soil under the topsoil. =Sulphur=: a yellowish chemical element; brimstone. =Taproot=: the main root of a plant, which runs directly down into the earth to a considerable depth without dividing. =Terrace=: a ridge of earth run on a level around a slope or hillside to keep the land from washing. =Thorax=: the middle part of the body of an insect. The thorax lies between the abdomen and the head. =Thermometer=: an instrument for measuring heat. =Tillage=: the act of preparing land for seed, and keeping the ground in a proper state for the growth of crops. =Transplant=: a plant grown in a bed with a view to being removed to other soil; a technical term used by gardeners. =Tubercle=: a small, wart-like growth on the roots of legumes. =Udder=: the milk vessel of a cow. =Utensil=: a vessel used for household purposes. =Variety=: a particular kind. For example, the Winesap, Bonum, AEsop, etc., are different varieties of apples. =Ventilate=: to open to the free passage of air.