A third peculiarity which distinguishes the forests of the north from those of the tropical world is what may be called their harmless character. There the traveller finds none of those noxious plants whose juices contain a deadly poison, and even thorns and prickles are of rare occurrence. No venomous snake glides through the thicket; no crocodile lurks in the swamp; and the northern beasts of prey--the bear, the lynx, the wolf--are far less dangerous and blood-thirsty than the large felidæ of the torrid zone. The comparatively small number of animals living in the Arctic forests corresponds with the monotony of their vegetation. Here we should seek in vain for that immense variety of insects, or those troops of gaudy birds which in the Brazilian woods excite the admiration, and not unfrequently cause the despair of the wanderer; here we should in vain expect to hear the clamorous voices that resound in the tropical thickets. No noisy monkeys or quarrelsome parrots settle on the branches of the trees; no shrill cicadæ or melancholy goat-suckers interrupt the solemn stillness of the night; the howl of the hungry wolf, or the hoarse screech of some solitary bird of prey, are almost the only sounds that ever disturb the repose of these awful solitudes. When the tropical hurricane sweeps over the virgin forests, it awakens a thousand voices of alarm; but the Arctic storm, however furiously it may blow, scarcely calls forth an echo from the dismal shades of the pine-woods of the north. In one respect only the forests and swamps of the northern regions vie in abundance of animal life with those of the equatorial zone, for the legions of gnats which the short polar summer calls forth from the Arctic morasses are a no less intolerable plague than the mosquitoes of the tropical marshes. [Illustration: 9. FOREST CONFLAGRATION.] Though agriculture encroaches but little upon the Arctic woods, yet the agency of man is gradually working a change in their aspect. Large tracts of forest are continually wasted by extensive fires, kindled accidentally or intentionally, which spread with rapidity over a wide extent of country, and continue to burn until they are extinguished by a heavy rain. Sooner or later a new growth of timber springs up, but the soil, being generally enriched and saturated with alkali, now no longer brings forth its aboriginal firs, but gives birth to a thicket of beeches (_Betula alba_) in Asia, or of aspens in America.