EXPERIMENTAL PSYCHOLOGY 



continuous filament could do precisely as in the case 

 of an electric wire. 



This conception, founded on a most tangible ana- 

 tomical basis, enables us to answer the question as to 

 how ideas are isolated, and also, as Dr. Cajal points out, 

 throws new light on many other mental processes. 

 One can imagine, for example, by keeping in mind the 

 flexible nerve prolongations, how new trains of thought 

 may be engendered through novel associations of cells ; 

 how facility of thought or of action in certain direc- 

 tions is acquired through the habitual making of cer- 

 tain nerve-cell connections ; how certain bits of knowl- 

 edge may escape our memory and refuse to be found 

 for a time because of a temporary incapacity of the 

 nerve cells to make the proper connections, and so on 

 indefinitely. 



If one likens each nerve cell to a central telephone 

 office, each of its filamentous prolongations to a tele- 

 phone wire, one can imagine a striking analogy between 

 the modus operandi of nervous processes and of the tel- 

 ephone system. The utility of new connections at the 

 central office, the uselessness of the mechanism when 

 the connections cannot be made, the "wires in use" 

 that retard your message, perhaps even the crossing of 

 wires, bringing you a jangle of sounds far different from 

 what you desire all these and a multiplicity of other 

 things that will suggest themselves to every user of 

 the telephone may be imagined as being almost ludi- 

 crously paralleled in the operations of the nervous 

 mechanism. And that parallel, startling as it may 

 seem, is not a mere futile imagining. It is sustained 

 and rendered plausible by a sound substratum of knowl- 



285 



