316 CELL INTELLIGENCE THE CAUSE OF EVOLUTION 



frog raises its hind foot to brush away a needle or a drop 

 of acid on its side ; if the leg on that side were amputated, 

 the other leg would display purposive endeavor to remove 

 the object. 



"It is difficult to appreciate properly the complexity of 

 reflex action. Many movements which seem to exhibit 

 all the purposive guidance of the deliberate will are noth- 

 ing but reflex actions, which were at first consciously 

 willed and often sink to the level of reflexes, such as 

 walking, writing, balancing and many other muscular 

 movements. 



"Laws of Central Nervous Action Whenever a sens- 

 ory stimulus is transmitted to a central nerve cell, the 

 force is never lost but intends to flow out again in motor 

 action. By central nerve cells we here mean ganglia in 

 either the brain or the spinal cord. Whenever a sensory 

 stimulus pours into nerve cells, there will be a tendency 

 for it to pass out in motor action, which causes muscular 

 movement. This law holds equally good for conscious 

 or unconscious stimuli. 



"No reflex action shows the presence of will in its 

 higher deliberative form, although purposive reflexes may 

 indicate a time when they were the slowly formed prod- 

 ucts of all the individuals, intelligence and will power. 



"Instinctive action Whenever a conscious sensation, 

 due either to external or internal stimuli results in pur- 

 posive action toward a given end, (which is not forseen) 

 that action is instinctive. 



"A young stork left alone in a northern latitude would 

 emigrate southward on approach of winter; had the bird 

 never been south before, it could have no idea of the pur- 

 pose of its flight although its actions were directed 

 toward an intelligent end. Certain sensations of organic 

 origin prompt the young bird to build its first nest. This 



