While there is thus very little or in fact almost no struggle for water in the rain forest, the struggle for light is intense. In the deepest and most luxuriant of them the gloom of the forest floor is notorious and it was by no means a figure of speech for Stanley to describe his trip through equatorial Africa as “Through the Dark Continent.” So dark are most rain forests, and, as we have seen in a previous chapter, so inexorable are the plants’ demands for light, that the various devices to insure it are perhaps the one great difference between these forests and those of temperate regions. One effect of the struggle for light is the enormous production of vines often running hundreds of feet through the tree tops. In India the _Calamus_, or rattan palms, with stems no thicker than a walking-stick, will completely interlace the foliage of the canopy. Thousands of slender whiplike roots and stems of such plants descend from the topmost heights of the forest canopy, where the plants to which they are attached make such an inextricable tangle among the tree tops that orchid collectors have been known to travel considerable distances over the matted vegetation, with, it must be confessed, considerable danger. These vines or _lianes_ as they are called, are however, often as thick as a man’s body and armed with great hooked prickles, an obvious aid in catching some support to reach that essential light for which all plants in such places are ever striving. Besides the bewildering tangle caused by these lianes, the rain forest is further impeded by hosts of epiphytes or plants that are mechanically attached to tree trunks, branches, or anything else that will raise them to the light. Of all the plants of such regions the epiphytes are the most light-demanding. They must not be mistaken for parasites, as they have roots of their own through which they absorb nourishment, mostly as water vapor, but also as liquid water held in the bark and refuse in which they grow. Thousands of orchids are epiphytes, also ferns, and, only in the American tropics, thousands of different relatives of the pineapple. Many of the latter are among the most gorgeously colored of all plants, their superb foliage being much sought after and the specimens largely grown in our greenhouses. In most rain forests every available inch of space is covered by these epiphytes, so that no bark, scarcely any branches, are to be seen but those clothed in this motley array of plants that use the support to get the utmost possible light. Many of these epiphytes have rosettes of leaves arranged for holding water, and after a sharp thunder shower followed by fresh wind the writer has seen the ground strewn with thousands of relatives of the pineapple which, with the added supply of water, were unable to stand the strain and were consequently wrenched from their lofty perch. So enormous is the combined weight of these epiphytes, together with the