In descriptions of natural objects or scenery, both in the manner of viewing the phenomena, and in the choice of the expressions employed to describe them, this truth to nature must ever be kept in view as the guiding aim: its attainment will be at once most easily and most effectually secured by simplicity in the narration of what we have ourselves beheld or experienced, and by limiting and individualising the locality with which the narrative is connected. Generalisation of physical views, and the statement of general results, belong rather to the “study of the Cosmos,” which, indeed, must ever continue to be to us a science of Induction; but the animated description of organic forms (plants and animals) in their local and picturesque relations to the varied surface of the earth (as a small fragment of the whole terrestrial life) affords materials towards the study of the Cosmos, and also tends to advance it by the stimulus or impulse imparted to the mind when artistic treatment is applied to phenomena of nature on a great scale. Among such phenomena must certainly be classed the vast forest region which, in the tropical portion of South America, fills the great connected basins of the Orinoco and the Amazons. If the name of primeval forest, or “Urwald,” which has of late years been so prodigally bestowed, is to be given to any forests on the face of the earth, none can claim it perhaps so strictly as the region of which we are speaking. The term “Urwald,” primitive or primeval forest, as well as Urseit and Urvolk,--primitive age, primitive nation,--are words of rather indefinite meaning, and, for the most part, only relative import. If this name is to be given to every wild forest full of a thick growth of trees on which Man has never laid a destroying hand, then the phenomenon is one which belongs to many parts of the temperate and cold zones. But if the character of the “Urwald” is that of a forest so truly impenetrable, that it is impossible to clear with an axe any passage between trees of eight or twelve feet diameter for more than a few paces, then such forests belong exclusively to the tropical regions. Nor is it by any means, as is often supposed in Europe, only the interlacing “lianes” or climbers which make it impossible to penetrate the forest; the “lianes” often form only a very small portion of the underwood. The chief obstacle is presented by an undergrowth of plants filling up every interval in a zone where all vegetation has a tendency to become ligneous. An impatient desire for the fulfilment of a long cherished wish may sometimes have led travellers who have only just landed in a tropical country, or perhaps island, to imagine that although still in the immediate vicinity of the sea-shore they had entered the precincts of a primeval forest, or “Urwald,” such as I have described as impenetrable. In this they deceived themselves; it is not every tropical forest which is entitled to an appellation which I have