earth, has its epochs, as well as that of the migrations of the animal world.
Yet although organic life is everywhere diffused, and the organic powers are incessantly at work in reconnecting with each other the elements set free by death or dissolution, the abundance and variety of organised beings, and the rapidity with which they are renewed, differ in different climates. In the cold zones, the activity of organic life undergoes a temporary suspension during a portion of the year by frost; fluidity is an essential condition of life or vital action, and animals and plants, with the exception of mosses and other cryptogamia, are in those regions buried for several months of each year in winter sleep. Over a large part of the earth, therefore, there could only be developed organic forms capable of supporting either a considerable diminution of heat, or, being without leaves, a long interruption of the vital functions. Thus we see variety and grace of form, mixture of colours, and generally the perpetually youthful energy and vigour of organic life, increase as we approach the tropics. This increase can be denied only by those who have never quitted Europe, or who have neglected the study of physical geography. When, leaving our oak forests, we traverse the Alps or the Pyrenees, and enter Italy or Spain, or when we direct our attention to some of the African shores of the Mediterranean, we might easily be led to draw the erroneous inference that hot countries are marked by the absence of trees. But those who do so, forget that the South of Europe wore a different aspect on the first arrival of Pelasgian or Carthaginian colonies; they forget that an
