Page:Literary pilgrimages of a naturalist (IA literarypilgrima00packrich).pdf/224

 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