The small lots of seeds developed by crossing are usually kept in flower-pots mixed with sand (5. Seed-stratification). When the seedlings produced are one year old the tops can be cut off just above the crown late in autumn and used the next spring for top-working on young bearing-trees of the same species (88. Top-grafting). By ringing (40. The Fruit and its Maturation) the branch after it has made two years' growth we can usually secure fruit for testing the third year. The seedling crosses cut back will start from the stub the next spring and can be used to determine the relative thrift and hardiness of the new variety on its own roots.