Not a tree was left standing, and every log went to ashes. The burn was as completely cleared as a fireswept prairie; in places there were holes in the earth where tree-roots had burned out. This burn was an ideal place for another lodge-pole growth, and three years later these pines were growing thereon as thick as wheat in a field. In a boggy area within the burn an acre or two of aspen sprang up; this area, however, was much smaller than the one that the fire removed from the bog. Aspens commonly hold territory and extend their holdings by sprouting from roots; but over the greater portion of the bog the fire had either baked or burned the roots, and this small aspen area marked the wetter part of the bog, that in which the roots had survived. After destroying the lodge-pole growth the fire passed on, and the following day it burned away as a quiet surface fire through a forest of scattered trees. It crept slowly forward, with a yellow blaze only a few inches high. Here and there this reddened over a pile of cone-scales that had been left by a squirrel, or blazed up in a pile of broken limbs or a fallen tree-top; it consumed the litter mulch and fertility of the forest floor, but seriously burned only a few trees. Advancing along the blaze, I came upon a veteran yellow pine that had received a large pot-hole burn in its instep. As the Western yellow pine is the best fire-fighter in the conifer family, it was puzzling to account for this deep burn. On the Rocky Mountains are to be found many picturesque yellow pines that have a dozen times triumphed over the greatest enemy of the forest. Once past youth, these trees possess a thick, corky, asbestos-like bark that defies the average fire. Close to this injured old fellow was a rock ledge that formed an influential part of its environment; its sloping surface shed water and fertility upon its feet; cones, twigs, and trash had also slid down this and formed an inflammable pile which, in burning, had bored into its ankle. An examination of its annual rings in the burned hole revealed the fact that it too had been slightly burned fifty-seven years before. How long would it be until it was again injured by fire or until some one again read its records? Until recently a forest fire continued until stopped by rain or snow, or until it came to the edge of the forest. I have notes on a forest fire that lived a fluctuating life of four months. Once a fire invades an old forest, it is impossible speedily to get rid of it. "It never goes out," declared an old trapper. The fire will crawl into a slow-burning log, burrow down into a root, or eat its way beneath a bed of needles, and give off no sign of its presence. In places such as these it will hibernate for weeks, despite rain or snow, and finally some day come forth as ferocious as ever.