SYSTEMATIC ANALYSIS OP APPARATUS. 63 



special sensatory organs, upon their nerves, that in turn 

 excite the ganglia, formed in part of their inner extrem- 

 ities. In this case by three steps the activity is excited. 



8th. JBy the action of objects exerting an influence 

 upon the organs. In this case there are four steps be- 

 tween cause and activity ; for example, an object throws 

 light upon the eye, through it aftecting its special nerve, 

 that acts upon its ganglion. 



153. THE ORDER OF THE PRODUCTION OF SENSATION 



may be represented as follows : 



Cause. 



Mind, Ganglia, Mind, 



Sensation. 

 Cause. 

 Ganglia, Mind, 



Sensation. 

 Cause. 

 Nerve, Ganglia, Mind, 



Sensation. 

 Cause. 



General Organ, Nerve, Ganglia, Mind, 

 Sensation. 



Cause. 



Special Organ, Nerve, Ganglia, Mind, 

 Sensation. 



Cause. 



Object, Special Organ, Nerve, Ganglia, Mind, 

 Sensation. 



Cause. 



Object, Influence, Special Organ, Nerve, Ganglia, Mind, 



Sensation. 



Parts of Body. 



154. IN THE PRODUCTION OF A SENSATION IT IS EVI- 

 DENT that one, two, or three parts of the body are always 

 concerned ; they are called Sensatory Organs, or Organs 

 of Sensation. 



155. A COMPLETE SENSATORY APPARATUS is COM- 

 POSED of three kinds of Sensatory Organs ; thus, 



Sensatory Apparatus. 



General or Special Organ, Nerve, Ganglion. 



8th? 153. Write table and explain. 154. What ? 155. Of what ? Howls 

 sensation caused? 



