166 THE RIDDLE OF THE UNIVERSE. 



the hydromedusae, we can observe a double soul : the 

 personal soul of the numerous individualities which 

 compose them, and the common, harmoniously-acting 

 psyche of the entire colony. 



IV. The nerve-soul ( neuropsyehej ; fourth stage of 

 phyletic psychogeny. — The psychic life of all the 

 higher animals is conducted, as in man, by means of a 

 more or less complicated "psychic apparatus." This 

 apparatus is always composed of three chief sections : 

 the organs oj sense are responsible for the various 

 sensations ; the muscles effect the movements ; the 

 nerves form the connection between the two by means 

 of a special central organ, the brain or ganglion. 

 The arrangement and action of this psychic mechanism 

 have been frequently compared with those of a tele- 

 graphic system ; the nerves are the wires, the brain 

 the central, and the sense-organs subordinate stations. 

 The motor-nerves conduct the commands of the will 

 centrifugally from the nerve-centre to the muscles, 

 by the contraction of which they produce the move- 

 ments : the sensitive nerves transmit the various 

 sensations centripetally — that is, from the peripheral 

 sense-organs to the brain, and thus render an account 

 of the impressions they receive from the outer world. 

 The ganglionic cells, or " psychic-cells," which com- 

 pose the central nervous organ, are the most perfect 

 of all organic elements ; they not only conduct the 

 commerce between the muscles and the organs of 

 sense, but they also effect the highest performances 

 of the animal soul, the formation of ideas and 

 thoughts, and especially consciousness. 



The great progress of anatomy, physiology, histo- 

 logy, and ontogeny has recently added a wealth of 

 interesting discoveries to our knowledge of the 



