CRILE— THEORY OF PROCESSES. 549 



that the nerve-cell battery like other batteries could not create 

 electricity continuously, but would require periods of rest for re- 

 charging. These periods of discharging and of recharging are re- 

 spectively periods of consciousness and of sleep. We know that 

 fatigue and death result from prolonged deprivation of sleep. 

 The changes within the brain and the liver cells are evidenced by 

 swelling; by a striking diminution of differential stainability and, 

 as we shall show later, by changes in their electric conductivity. 

 We would expect that the fatigue (weariness) produced by activity 

 would be restored by sleep. That this is so is shown by common 

 experience and by histologic and conductivity findings. 



TJ^e principal parts of the cell are (a) water; (b) salts in solu- 

 tion; (c) selective semi-permeable membranes. 



Water. — Life is coextensive with water; water is the vehicle in 

 which life is suspended. Perhaps the strongest evidence in favor 

 of the electro-chemical theory may be found in a consideration of 

 the properties of water. Of highest significance is the fact that 

 water is a non-conductor of electricity. This property is essential 

 for the accumulation of electric charges ; it is essential for the for- 

 mation of colloids. Colloids are essential to life. Water is the 

 greatest solvent. Water is the greatest catalyst, hence water is 

 the vehicle best adapted for the storage of energy. Suspensions 

 and solutions are electrical processes. We have therefore as the 

 physical basis of every cell a non-conducting medium in which 

 are suspended electrically charged particles. In free colloids or in 

 solutions, the electric energy is evenly diffused. To create, to store, 

 and to discharge energy for adaptive purposes, an additional struc- 

 ture is required. This structure consists of the lipoid selective 

 semi-permeable membranes surrounding the cell as a whole, sur- 

 rounding the nucleus, and surrounding the spherules lying in the 

 layer compartments. Why were the membranes evolved to be 

 selective semi-permeable membranes ? So that oxygen and activating 

 agents may enter, in order that potential energy may be created 

 within the cell ; and that there may be a suitable riddance of damag- 

 ing compounds. 



The activity of the nerve cell is dependent in large measure 

 upon oxidation. W'e would expect that the energy of the cells 



