622 Causes and Course of Organic Evolution 



But when one watches the movements of any mammal up 

 to the monkeys a helpful interpretation seems forthcoming. 

 For, when a fruit or other food is presented, the eyes in connec- 

 tion with the optic lobes form a rapid and cumulated response 

 activity. But the discriminating — one might almost say the 

 intelligent — handling of the fruit in front of the nose, before 

 any effort is made to eat it, is proof that the earliest formed of 

 the animal sense centers is also that which retains the most 

 fundamental importance. All again who have noted, as has 

 the writer, the rapid and usually unerring sweep of a pack of 

 hounds, over four or five miles of rough land, when led only by 

 an invisible and faint trail of animal skin, can realize how im- 

 portant the olfactory center has been in the upward evolution 

 of mammals. Though man has often allowed his primary 

 sense function to lapse somewhat, owing to varied use of the 

 hand, of the eye, and of taste, this merely indicates a transfer 

 of sense-activity and response from one center to another. 



Reason, as the term is ordinarily used, represents a steady 

 advance on Intelligence, as the latter is on Instinct. It is a 

 phenomenon of nerve cells in which these depend more and 

 more on inherited associative tendencies, instincts, and ac- 

 quired intellectual percepts; less and less on direct, and indi- 

 vidual, peripheral stimulation of the sense organs. Holmes 

 says (p. 274): "If we define reason as the derivation of conclu- 

 sions through the comparison of concepts, it is not improbable 

 that no animal below man employs this faculty. But this is 

 far from imi)lying that animals cannot perform mental opera- 

 tions, which are essentially inferential in their nature. Reason 

 is not a faculty which stands sharply marked off from other 

 forms of mental activity. Between simple perception on the 

 one hand and abstract ratiocination on the other there is a 

 fundamental kinship, and the latter process may be connected 

 with the first by numerous intermediate stages." 



So between percepts that have been gradually linked up 

 into complex resultant percepts that start an intelligent re- 

 sponse, l)ut which at the same time so mold the nerve cells as 

 to cause these, even on future faint stimulation, to evolve like 



