The true virgin forests, notwithstanding the recent explorations of Wallace, Bates, and Agassiz, are very imperfectly known; because it is, in truth, perfectly impossible to survey them in every direction, on account of their vast extent and astonishing impenetrability. When we are told by the traveller that he opened for himself a path with his trusty hatchet, we readily understand that he achieved his boasted victory in places where the obstacles were reduced to feeble lianas and brushwood of no great density, and that he turned aside from the massive barriers formed by the closely-planted trunks of colossal trees. Than these mighty vegetable Anakim, nothing, says a naturalist, is more imperfectly known in botany. The stems of most being bare and branchless up to a considerable height, their fructification is frequently beyond the reach of man. In vain would he level them by their base: their summits remain suspended by the inter-tanglement of the neighbouring summits, and like so many Tantaluses, our travellers see themselves shunned by the fruits which their eyes devour. The rivers, those "tracks which march" through the leafy, woody depths, and the tortuous paths trodden down by generations of wild beasts in their quest after new pastures, after fresh hunting-grounds, or fountains to slake their thirst, are the only roads which can be pursued by the explorer. [Illustration: THE VIRGIN FOREST IN BRAZIL.] As far as concerns their botanical composition, the virgin forests of the Tropics are distinguished from those of cold and temperate regions by general characters which it will, perhaps, be useful to indicate. If, for example, we adopt as our standard of comparison the European forest, we there remark, in the first place, the complete absence of trees belonging to the important groups of Acotyledons and Monocotyledons, and, in consequence, of the superb palms and elegant arboreal ferns of tropical countries. Or, considering only the Dicotyledonous plants, we see again that, in lands bordering on the Equator, there is scarcely a family of this class which does not furnish its contingent of woody plants, offering most frequently, with forms of infinite variety, clearly displayed and brilliant flowers, remarkable either for their beauty or their fragrance,-- "Sweet as Sabæan odours from the shores Of Araby the Blest;" while our trees are comprised in a small number of natural groups, and present in general very opposite features; as, for instance, an almost uniform character or aspect, and flowers scarcely visible and of little elegance.