up to the tree limit—between thirteen and fourteen thousand feet. Spruce trees thrive best above the ten-thousand-foot line. There is very little undergrowth and the country is park-like. The absence of animal life is noticeable. Ants, flies, mosquitos, birds and mammals that are so abundant in most parts of the world are rare here. The only reptiles that I saw were occasional salamanders. The slopes are easy and regular, so that little energy is wasted by the necessity of descending from heights once reached.
During the day shifting clouds revealed one beauty after another by blotting out one portion of the heavens or mountains and calling attention to others. Occasionally the splendid summit of Orizaba would appear, then the top of a neighboring mountain, as if nature were trying
the effect of draperies. Sometimes the clouds would envelop us with their cold folds and shut out from view all but the nearest trees. At four in the afternoon, though much too early according to my judgment, we halted and prepared a camp under the shelter of a cliff, whose base is hollowed out in the form of a shallow cave. It affords poor protection. The rain coming from one direction is shut off, but water drips from the rocks. Just after darkness had begun to settle down we heard a far-away shout as if from some one in distress. We answered and soon found that it was simply a shepherd calling his flock. It was a cold night and sleeping out of doors at that altitude is not a luxury. In the morning my rubber blanket was stiff with a sheet of ice.