ORGANIC EVOLUTION 



357 



of which the record is fairly well preserved. Moreover, the 

 records show that the atavus of the horse began in North 

 America, and that by migration the primitive horses spread 

 from this continent to Europe, Asia, and Africa. 



So far we have treated the question of fixity of species as 

 a historical one, and have gone searching for clues of past 



a 



c 



FIG. 1 06. Bones of the Foreleg and Molar Teeth of Fossil Ancestors 

 of the Horse. European Forms. (After Kayser.) 



conditions just as an archaeologist explores the past in buried 

 cities. The facts we have encountered, taken in connection 

 with a multitude of others pointing in the same direction, 

 begin to answer the initial question, Were the immense num- 

 bers of living forms created just as we find them, or were 

 they evolved by a process of transformation ? 



