308 GENERAL BIOLOGY 



record, we find that without exception it tells the 

 story of one type replacing another, and of simple 

 types giving place to more and more complex. 

 Patiently, fragment by fragment, the records of the 

 rocks have been brought together until we now have, 

 for example, the nearly complete genealogy of the 

 horse, dating back to a five-toed ancestor, not much 

 bigger than a rabbit. 



History of the Elephant. A very good example 

 of the successive changes in the transformation of 

 one type into another is to be found in the elephant 

 and its genetic predecessors. The ancestor of the 

 modern elephant, the remains of which have been 



ramifying branches may well represent the classification of all extinct 

 and living species in groups subordinate to groups. Of the many twigs 

 which flourished when the tree was a mere bush, only two or three, now 

 grown -into great branches, yet survive and bear the other branches, 

 so with the species which lived during long past geological periods. very 

 few have left living and modified descendants. From the fir>t ^rnuih 

 of the tree, many a limb and branch has decayed and dropped otT; ;in<l 

 fallen branches of various sizes may represent those whole orders. 

 families, and genera which have now no living representatives, and whirh 

 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 on the tree, and which 

 by some chance has been favored 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 >id-s 

 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 < ni>t 

 of the earth, and covers the surface with its everbranching and beautiful 

 ramifications." DARWIN, "The Origin of Species," Chapter IV. 



