THE STORY OF NINETEENTH-GENT UK Y SCIENCE 



This conception, founded on a most tangible anatom- 

 ical 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 flexi- 

 ble nerve prolongations, how new trains of thought may 

 be engendered through novel associations of cells ; how 

 facility of thought or of action in certain directions is 

 acquired through the habitual making of certain nerve 

 cell connections; how certain bits of knowledge 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, he 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 ludicrously 

 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 knowledge of the anatomical 

 conditions under which the central nervous mechanism 

 exists, and in default of which, as pathology demonstrates 

 with no less certitude, its functionings are futile to pro- 

 duce the normal manifestations of higher intellection. 



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