The sugar maple reaches maturity at about a hundred years. Then in the forest the trees are seventy to eighty feet tall and have a diameter of two to four feet. Trees grown from seed produce the sweetest sap, second growth not being so good. The seedling under favorable conditions may reach a diameter of sixteen inches in fifteen years, though such growth is exceptional. It is not profitable to tap them before the age of twenty. After that they may be drawn from yearly, a tap to a tree at first. On the largest trees two or more buckets may be hung, never one above the other, as the sap flows up or down, never sidewise. The sweetest and best sap comes from the outermost ring of growth, the wood of the previous year. It is sweetest at the height of the run. It flows better by day than by night; the brighter, lighter and sunnier the day the faster it flows, the trees resting more or less at night. As the sun declines, so does the flow, even when the temperature remains the same. On warm nights, however, there is likely to be some flow. Daytime sap is sweetest, and the nearer the occurrence of a freeze or a snowstorm the sweeter the sap. Light seems to be a powerful agent in the mystery, but a certain balance of heat and cold is more powerful still. Freezing nights with alternating warm days bring the ideal conditions, frozen roots and warm twigs setting the alchemy at work. Yet with all this and much more general knowledge to draw from each grove is a study. The maples are strongly individualistic, and every tree is a law unto itself. Some have a much higher percentage of sugar to the same amount of sap than others. Indeed, it is confidently predicted by experts that a race of superior trees could be easily developed by taking seed from those of highest sugar percentage, just as superior fruit trees are thus bred. The profit to the sugar-maker from this is obvious. The future may see it done. As conditions exist the average yield of sugar per tree is from two to three pounds, though in favorable seasons this is increased in some groves to five or six pounds. On the other hand there are records of large trees which have yielded as much as forty pounds of sugar in a season, and many have been known to give twenty pounds. Sometimes a certain tree on a farm gets to be known as “the sweet tree,” because of the large amount of sugar it yields yearly.