CHAP. IX The Divided Labours of the Body 149 



the outgoing nerves, and cause muscular move 

 ments, or the activity of glands, or other cellular 

 activities. 



In many ways analogous to the nervous system is 

 the telegraph system of a country ; the receiving stations 

 are the nerve cells, among which are the cells of the sense 

 organs ; the connecting wires are the nerve fibres ; the 

 central stations are the groups of cells called ganglia, the 

 chief of which are in the brain and spinal cord. The less 

 important ganglia are like the branch offices, they receive 

 messages and transmit them unaltered ; the higher ganglia 

 are like the offices of a government, in which messages are 

 received, plans elaborated on the strength of the news, and 

 orders sent out to various parts of the country. All such 

 actions when they take place in the nervous system are 

 called reflex actions, whether a received message be sent 

 on unaltered, or whether the receiving cell regulates the 

 transmission according to the needs of the parts of the 

 body. The analogy of telegraph stations, even with the 

 living clerk to work them and with responsible persons to 

 direct the clerk, does not give a much too complex idea of 

 the activities of nerve cells. 



3. Sketch of Psychology. — The following is largely 

 derived from Professor Lloyd Morgan's Animal Life and 

 Intelligence, to which we refer the reader, and to which we 

 acknowledge our indebtedness. 



It very often happens that changes in nervous matter, 

 caused by changes in the outer world, result in what we 

 call a change of consciousness. 



Consciousness is the subjective side of molecular dis- 

 turbance in brain or other nerve matter. 



Changes in the outer world which cause disturbance of 

 nerve matter are called stimuli. 



Changes of consciousness produced by stimuli are called 

 impressions. 



If impressions left no permanent trace in conscious- 

 ness behind them, there would be no such thing as mind. 

 For mind is based upon memory, and memory is the re- 

 vival of past impressions, which, we must suppose, have in 



