I pRODY CT ION. 
By the Evolution of Life we mean the slow and gradual 
development of life as distinguished from its special and 
sudden creation; that plants and animals are the modified 
descendants of pre-existing organisms, not the unchanged 
posterity of similar forms of life originally specially cre- 
ated. Let us illustrate our meaning by considering the 
origin of a common animal like the Horse. According to 
the creation hypothesis, all horses are the descendants of a 
pair of horses, originally, specially created. Supposing the 
Evolution theory, however, to be true, the Horse is the 
modified descendant of an extinct species of Horse, the 
Hipparion. Preceding the Hipparion there lived the An- 
chitherium, whose organization bears the same relation to 
the Hipparion that the Hipparion’s does to that of the 
Horse; while in a still earlier period we find in the 
Paleotherium the ancestor of the Anchitherium. But the 
Rhinoceros and the Tapir are also nearly related to the 
Paleotherium. We see, therefore, why all naturalists are 
agreed in regarding the Horse, Rhinoceros, and Tapir as the 
tatives of one group. For, if these animals are the 
ei of a common ancestor, it is natural that their 
organization should have much in common. Through 
extinct forms, like the Xiphodon and Anthracotherium, the 
Ruminating animals, the Pig, and the Hippopotamus, are 
linked with the Anoplotherium; while glancing at Tree 
VII. we see that the Paleotherium and Anoplotherium are 
) 
