Chap. IV] SUMMARY. 163 



living and modified descendants. From the first growth 

 of the tree, many a limb and branch has decayed and 

 dropped off; and these fallen branches of various sizes 

 may represent those whole orders, families, and genera 

 which have now no living representatives, and which 

 are known to us only in a fossil state. As we here and 

 there see a thin straggling branch springing from a fork 

 low down in a tree, and which by some chance has been 

 favoured and is still alive on its summit, so we occasionally 

 see an animal like the Ornithorhynchus or Lepiclosiren, 

 which in some small degree connects by its affinities two 

 large branches of life, and which has apparently been 

 saved from fatal competition by having inhabited a 

 protected station. As buds give rise by growth to fresh 

 buds, and these, if vigorous, branch out and overtop on 

 all sides many a feebler branch, so by generation I 

 believe it has been with the great Tree of Life, which fills 

 with its dead and broken branches the crust of the 

 earth, and covers the surface with its ever-branching 

 and beautiful ramifications. 



