Another interesting matter for spring observation is the relative times of the bursting of the flowering buds and the leafing buds on the same species of tree or shrub. In many cases the former are fully developed before the latter show any signs of active growth, or while the foliage is as yet only passing through its earliest stages. The Hazel catkins shed their abundance of pollen before the foliage buds show the slightest signs of green. The Blackthorn is white with snowy blossoms before a leaf appears. The upper twigs of the Elm appear fluffy in the distance through the formation of its flowers while the foliage buds are still dormant; and the Alder, Willow, Poplar and Aspen likewise produce full-blown catkins while their branches are otherwise bare. Of the trees above named, the Hazel, Elm, Alder, Poplar, and Aspen are dependent on the spring winds for the transfer of the pollen, but the pollination of the Willow and the Blackthorn is brought about by the agency of early insects which visit the flowers for the nectar they provide. [Illustration: SEEDLING OF THE BEECH, SHOWING THE COTYLEDONS AND THE FIRST FOLIAGE LEAVES.] The same spring sun which calls forth the new leaves and early flowers exerts its vivifying influence on the seeds that fell to the ground before the winter's frosts set in, and in sheltered places myriads of young seedlings of plants and trees may be found in their first stages of growth. The early history of a plant is as interesting a study as that of the mature specimen, and the young botanist will do well if he seeks out the germinating seeds and watches their development. This part of botanical study may, perhaps, be carried on more conveniently at home than in the field, for the seedlings may be grown in soil, wet sawdust, or in water alone, and the stages closely observed. The seed is a plant in embryo. It consists of a young root, a bud, and one or two seed-leaves or cotyledons. Some seeds contain nothing but the parts just named, and when this is the case the cotyledons contain a reserve of food material sufficient to maintain the developing plant until the root is enabled to absorb sufficient nutriment from the soil, and the first foliage leaves are so far advanced that they can absorb carbonic acid gas from the air, and build up with the aid of this gas, together with the food obtained from the soil, the compounds required by the growing plant. Other seeds contain, in addition to the embryo, a reserve of nutrient material quite distinct from it; and in such instances the cotyledons have the power of taking up this reserve, changing it to a condition suitable to the requirements of the plant, and then distributing it to the growing parts.