CHAPTER XIV. 

 THE ORIGIN OF SENTIENT LIFE. 



A BEING endowed with sentience is a phenomenon 

 of which the Evolution Hypothesis must give 

 intelligible account, or confess that it is unable to in- 

 terpret some of the most obvious facts in nature. In 

 this chapter we shall examine the question only in 

 relation to the lower animals, leaving for separate 

 discussion the origin and growth of self-conscious in- 

 telligence. 



Sentient life is best exemplified in some of its more 

 advanced forms. In the very lowest kinds it may be 

 difficult to distinguish with certainty the animal from 

 the vegetable. But when we turn to the more highly 

 organized beings, the differences between the two 

 kingdoms are so great that we are embarrased to find 

 characteristics common to both. Take the dog as an 

 example. The facts which await explanation are (a) 

 his intelligence, (6) his sense of pleasure and pain, 

 (c) his complex and highly developed organism. Put- 

 ting aside the question of intelligence, which will be 

 best examined in its highest form in man, we shall 

 test Mr. Spencer's theory by its success in giving 

 account of the origin of the organism and its seiisi- 



