304 Animal Life and Intelligence. 



by afferent nerves, from the organs of special sense, and 

 handing over the resultants by efferent nerves to the 

 organs of special activities. So far we have purely 

 physiological effects, many of which occur with surprising 

 accuracy and precision when an organism is in a state of 

 unconsciousness. Place your finger in the palm of a 

 sleeping child, and the fingers will close over it without 

 the child awaking to consciousness. If, in a frog, the 

 brain of which has been extirpated, the side be touched 

 with a drop of acid, the leg of that side will be drawn up, 

 and the foot will be used to wipe away the acid. And if 

 that leg be held and prevented from reaching the side, the 

 other leg will be brought round so as to try and bring the 

 foot within reach of the irritated spot. The actions are, 

 however, in all probability, purely physiological, and are 

 performed in complete absence of consciousness. 



When we turn from the physiological to the psycho- 

 logical aspect of the question, we enter a new world, the 

 world of consciousness, wherein the impressions received 

 by the recipient organs (no longer regarded as mere stimuli, 

 but as the elements of consciousness) are co-ordinated and 

 organized, and are built up into those sensations and 

 perceptions through which the objects of the external 

 world take origin and shape. It is with this process that 

 we have now to deal; and we will deal with it first in 

 man. 



The first fact to notice is that, apart from sense-stimuli 

 received and exciting consciousness, we have also the 

 revival of past impressions. This revival is the germ of 

 memory. What exactly is the physical basis of memory, 

 how the effects of stimuli in consciousness come to be 

 registered, we do not know. It is clearly a matter that 

 falls under the general law of persistence ; but in what 

 organic manner we are largely ignorant. Still, there can 

 be no question of the fact that, quite apart from impres- 

 sions due to immediate influences of the environment now 

 acting on our recipient organs, we have also revivals of 



