Those, therefore, who can view nature with a comprehensive glance and apart from local phenomena, may see from the poles to the equator organic life and vigour gradually augment with the augmentation of vivifying heat. But, in the course of this progressive increase there are reserved to each zone its own peculiar beauties; to the tropics, variety and grandeur of vegetable forms; to the north, the aspect of its meadows and green pastures, and the periodic reawakening of nature at the first breath of the mild air of spring. Each zone, besides its own peculiar advantages, has its own distinctive character. Primeval laws of organisation, notwithstanding a certain degree of freedom in the abnormal development of single parts, bind all animal and vegetable forms to fixed ever-recurring types. As we recognise in distinct organic beings a determinate physiognomy, and as descriptive botany and zoology, in the restricted sense of the terms, consist in a detailed analysis of animal and vegetable forms, so each region of the earth has a natural physiognomy peculiar to itself. The idea indicated by the painter by expressions such as “Swiss nature,” “Italian sky,” &c., rests on a partial perception of this local character in the aspect of nature. The azure of the sky, the lights and shadows, the haze resting on the distance, the forms of animals, the succulency of the plants and herbage, the brightness of the foliage, the outline of the mountains, are all elements which determine the total impression characteristic of each district or region. It is true that in every zone the same kinds of rocks, trachyte, basalt, porphyritic schists, and dolomite, form groups having the same physiognomy and aspect. The greenstone precipices of South America and Mexico resemble those of the Fichtel-Gebirge of Germany, just as among animals the form of the Allco, or native race of dogs of the New Continent, corresponds perfectly with that of the European race. For the inorganic crust of the globe shews itself independent of climatic influences; whether it be that differences of climate depending on differences of latitude were more recent than the formation of the rocks, or that the mass of the earth in solidifying and parting with its heat regulated its own temperature,[10] instead of receiving it from without. Thus all the kinds of rock with which we are acquainted may be met with in all parts of the globe, and everywhere affect the same characteristic forms. Everywhere basalt rises in twin mountains and truncated cones; everywhere the porphyritic trap appears in grotesquely arranged masses, and granite in rounded summits. Also similar forms of trees--pines and oaks--adorn the declivities of the mountains of Sweden, and those of the most southern part of Mexico.[11] Yet, notwithstanding these correspondences of form, and this similarity of outline in the component parts of the picture, their grouping gives to the whole the greatest difference of character.