Page:Excursions (1863) Thoreau.djvu/224

216 remember riding with one such citizen, who, though a fortnight too late for the most brilliant tints, was taken by surprise, and would not believe that there had been any brighter. He had never heard of this phenomenon before. Not only many in our towns have never witnessed it, but it is scarcely remembered by the majority from year to year.

Most appear to confound changed leaves with withered ones, as if they were to confound ripe apples with rotten ones. I think that the change to some higher color in a leaf is an evidence that it has arrived at a late and perfect maturity, answering to the maturity of fruits. It is generally the lowest and oldest leaves which change first. But as the perfect winged and^usually bright colored insect is short-lived, so the leaves ripen but to fall.

Generally, every fruit, on ripening, and just before it falls, when it commences a more independent and individual existence, requiring less nourishment from any source, and that not so much from the earth through its stem as from the sun and air, acquires a bright tint. So do leaves. The physiologist says it is "due to an increased absorption of oxygen." That is the scientific account of the matter,—only a reassertion of the fact. But I am more interested in the rosy cheek than I am to know what