10 PHYSIOGNOMY OF PLANTS. 



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 



