developed in man. He is less than any other being bound to any particular zone, and is further suited to the widest diffusion, because, confined to no especial food, he is, in the fullest sense of the word, omnivorous. He is, not only by the organization of his body, but especially by his mental power and his energetic will, fitted above all other creatures to accommodate himself to the most various influences that can affect him from without, and by continuous habitude to endure or make bearable the strangest conditions. He can live at the extreme limits at which organic life can exist, and can sustain a degree of cold at which quicksilver freezes. Thus, three Russians lived for seven years in Spitzbergen without suffering in health. Admiral Wrangell, while in the Chuckchee country in 1820, experienced a cold of nearly 50° below zero, while his men were as lively and happy as if it had been summer; and Parry and Franklin withstood a still greater cold. Man can also sustain an almost incredible degree of heat. The celebrated physician, Boerhaave, believed that no being breathing with lungs could live in an atmosphere having as high a temperature as that of the blood. According to this dictum, one ought to die at a temperature of 100°, but Banks enjoyed good health on the Senegal when the thermometer rose in his cabin to above 120° and 130°. Men live on the southwest coasts of Africa, and in other hot regions, where the heat of the sand under their feet reaches 140° or 150°. Men in deep mining-shafts and under diving-bells are able to support an atmospheric pressure of 30,000 kilogrammes as well as a pressure of only 8,000 kilogrammes on the highest mountains. Cassini thought that no animal could live at a greater height than 4,700 metres, or 15,000 feet; but there are several inhabited places situated at a still greater height, as, for instance, Gartok, in the Himalayas. Alexander von Humboldt ascended Chimborazo to a height of nearly 6,000 metres, or 19,286 feet, without suffering any harm. The pressure of the atmosphere is so light at such elevations that, as Humboldt was assured, wild animals when driven up to them bleed at the mouth and nose. Only the dog is able to follow man as far and as high as he can go; but this animal, too, loses his acute smell in Congo and Syria, and the power of barking in Surinam and at great heights; and the finer breeds of dogs can not long endure the conditions of a height of more than 3,760 metres, or 12,500 feet, while there are towns in the Andes at as great a height as 13,500 or 14,000 feet.
But there are regions in which even man perishes, to whatever race he may belong, and however well prepared he may be to resist their deadly influence. Among such regions is the Gaboon valley, in which even the negro is disabled. The inhabitants of that district are decidedly weaker in constitution, and have greatly diminished reproductive powers, and the women are considerably in excess. There are similar regions nearer the centers of civilization. The Tuscan Maremma is famous for its deadly air, and the swamps of Corsica are of like
