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A TEXTBOOK OF PHYSIOLOGY 



tradition. At one moment the man of genius may be conscious of 

 nothing but the desire to visit the privy, and at another moment he 

 may be conscious of the word which makes perfect a line of poetry. 



Consciousness leaves us when the brain is suddenly rendered 

 anaemic by closure of the carotid arteries. It leaves us in sleep, and 

 when a chemical agent, such as nitrous oxide or other anaesthetic, 

 interferes with the play of chemical and physical forces in the nervous 

 tissue. The nervous tissue acts as a transformer of energy, and when 

 it becomes inactive or is destroyed, that form of energy which we call 

 consciousness ceases. 



