As we proceed higher up the valley to an altitude of about 4,000 feet, European trees and plants begin to be intermingled with the tropical vegetation. Hornbeams appear, and birch, willow, alder, and walnut grow side by side with wild plantains, palms, and gigantic bamboos. Brambles, speedwells, forget-me-nots, and nettles grow mixed with figs, balsams, peppers, and huge climbing vines. The wild English strawberry is found on the ground, while above tropical orchids like the dendrobiums cover the trunks of the oaks. The bracken and the club-moss of our British moors grow associated with tree-ferns. And English grow alongside Himalayan mosses. The valley itself continues of the same character--deep with its steep sides clothed in forest and the path scrambling over spurs, making wide detours up side valleys, or scraping along the sides of cliffs which stand perpendicularly over the raging river below. Only here and there are clearings in the forest where Lepchas or Nepalese have built themselves a few wooden houses and roughly cultivated the land. Otherwise we are under the same green mantle of forest which extends everywhere over the mountains; and though we are now piercing straight through the main axis of the Himalaya, we seldom catch even a glimpse of the snowy heights which must be so near. But the vegetation is distinctly changing in character as we ascend--the most tropical trees and plants gradually disappearing, and more and more flowers of the temperate zone coming into evidence. And as we pierce farther into the mountains the climate becomes sensibly drier and the forest lighter. There is still a heavy enough rainfall to satisfy any ordinary plant or human being. But there is not the same deluge that descends upon the outer ridges. So the forest is not so dense. Frequently in its place social grasses clothe the mountain-sides; and yellow violets, primulas, anemones, delphiniums, currants, and saxifrages remind us of regions more akin to our own.