All parts of the earth's surface, even the deep recesses of caves and mines, the snows of the polar and alpine regions, and the bottom of the sea, are more or less covered with plants. The same may be said respecting animals, which, being much more diversified in their forms and internal structure, and endowed with more wonderful faculties, lead the mind, by the contemplation of their mechanism and habits, to a nearer approach to the great Creator of all things. From the gigantic elephant that roams among the splendid forests of the warmer regions of the earth, the unwieldy hippopotamus that plunges in the pools and marshes of the African wilds, and the timid and graceful giraffe that bounds over the sandy desert, down to the little dormouse that we find slumbering in its winter retreat, to the lemming that in congregated myriads overruns the fields of the North, or to the mole that burrows under our feet, we find an astonishing variety of beings, exhibiting forms, instincts, passions, and pursuits, which adapt them for the occupation of every part of the globe. The woods, the plains, the mountains, and the sands of the sea, are replete with life. The waters, too, whether of the ocean or of the land, teem with animated beings. Scarcely is a particle of matter to be found that does not present inhabitants to our view; and a drop of ditch-water is a little world in itself, stored with inmates of corresponding magnitude. The consideration of the anatomical structure and external conformation of the many thousands of living creatures that come under our view, would of itself occupy many volumes, were it presented in detail; and even the simplest outline in which it could be produced would require more space than can be devoted to it here. All departments of Nature are full of wonders; but this excels the rest in interest, and is proportionally more difficult to be studied; although men, contented with superficial knowledge, may fancy themselves masters of her secrets when they have merely learned to distinguish some hundreds of objects from each other. Man, separated from all other animals by peculiarities of corporeal organization, not less than by those intellectual faculties which are not in any considerable degree participated by the other inhabitants of the globe, and who is capable of subsisting in every climate, from the arid regions of the torrid zone to the frozen confines of the poles, also belongs in some measure to the study of nature. But the consideration of man includes a multitude of subjects that do not properly belong to Natural History, in the limited sense in which we use the term. It might even be said that it embraces all human knowledge. Thus, the constitution of the human mind, and the structure of the human body, as well as its healthy and morbid phenomena, together with the means of regulating the former and of counteracting the latter, may certainly be included in it.