HOW THE BRAIN THINKS 



of the brain and the nerves seems to be a highly 

 phosphorized fat, and without the phosphorus this 

 fat does not seem to think. 



The world of science was a long time accepting 

 the notion of a living substance, a chemically an- 

 alyzable basis of life. Huxley's celebrated " pro- 

 toplasm" lecture did much to reconcile men's 

 minds to this materialistic conception. But it has 

 been a great deal harder to bring men to conceive 

 of a thinking substance, a form of matter, like 

 salt or sugar or gunpowder, whose business it is 

 to feel and think and dream. To many the notion 

 is uncanny. 



The conclusion, however, seems inevitable. So 

 far as we know, the processes of thought and 

 consciousness are associated only with a special 

 form of living substance, a particular kind of 

 Huxley's "protoplasm." And protoplasm is a 

 more or less definite substance that can be, and 

 has been, analyzed in the chemist's tube. It is, 

 as we have seen, made up, in varying proportions, 

 of the water we drink, the oxygen and nitrogen of 

 the air we breathe, the carbon of the food we eat. 

 Add a trace of mineral salts, the salts of iron and 

 others, a little sulphur and phosphorus, and the list 

 of elements is complete. The analysis is difficult 

 not yet, perhaps, absolutely exact. 



But the main facts are clear. The chief constit- 

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