NEW CONCEPTIONS IN SCIENCE 



Isolde, the stuff it is made of is much the same ; it is 

 a difference of structure, apparently, rather than of 

 material. And the chemical difference between a 

 brain or nerve cell and that of the muscles or the 

 skin seems reducible, mainly, to a difference in the 

 proportion of two substances, water and phospho- 

 rus. Lean beef, for example, is from seventy to 

 eighty per cent, water; the brain is from ninety to 

 ninety-five per cent, water. And a brain or nerve 

 cell may contain from five to ten times as much 

 phosphorus as, let us say, the cells of the liver or 

 the heart. The actual quantity is, of course, ex- 

 tremely small, by weight but a fraction of one per 

 cent. 



About three pounds, avoirdupois, of this very 

 complex, phosphorized stuff make up an average 

 human brain. There is a lot more of it distributed 

 down one's spinal column; and in little plexi all 

 over the body, wherever a group of muscles are to 

 be moved ; and, again, in the motor and sensory or 

 feeling nerves, which are everywhere. It is hard to 

 find a cubical half -inch outside the bones where 

 they are not. 



All told, this nervous substance, which, for the 

 sake of making its functions clear, I have called 

 matter which thinks, forms a not inconsiderable 

 ]x>rtion of the body, outside of the bony skeleton. 

 It is made up of distinct and separated units, for the 



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