130 NATURAL SELECTION. Chap. IV. 



which are known to us only from having been found in 

 a fossil state. As we here and there see a thin strag- 

 gling 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 Lepidosiren, 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. 



