38 The Destiny of Man. 



the increasing intelligence and enlarged 

 experience of half-human man now set in 

 motion a new series of changes which 

 greatly complicated the matter. In order 

 to understand these changes, we must 

 consider for a moment one very important 

 characteristic of developing intelligence. 



The simplest actions in which the ner- 

 vous system is concerned are what we call 

 reflex actions. All the visceral actions 

 which keep us alive from moment to 

 moment, the movements of the heart and 

 lungs, the contractions of arteries, the 

 secretions of glands, the digestive opera- 

 tions of the stomach and liver, belong to 

 the class of reflex actions. Throughout 

 the animal world these acts are repeated, 

 with little or no variation, from birth un- 

 til death, and the tendency to perform 

 them is completely organized in the ner- 

 vous system before birth. Every animal 

 breathes and digests as well at the begin- 

 ning of his life as he ever does. Contact 

 tvith air and food is all that is needed, and 



