THE ROLE OF WATER 421 



ketogenic, i.e., high fat, low-carbohydrate, diet. If there is 

 less than one molecule of glucose for every two molecules of the 

 fatty acids in the diet, beta oxidation of the higher fatty acids 

 is incomplete with excessive formation of ketone bodies. Any 

 factor that reduces the semipermeability of the brain cells, e.g., 

 dehydration, acidosis and ketosis (increase in ketone bodies, such 

 as acetone, acetoacetic acid, and beta-hydroxybutyric acid), 

 retards the accumulation of fluid in the brain cells and the sub- 

 arachnoid spaces and thereby reduces, if it does not prevent, the 

 convulsions of epilepsy. During starvation, the largest loss in 

 body substance is water, with the production of a ketosis, because 

 of the small reserves of carbohydrates in the body. There is 

 uncertainty as to whether water loss or the disturbance of the 

 acid-base equilibrium is the primary factor in convulsions. But 

 we do know that a ketogenic diet decreases the permeability 

 of cell membranes and that a definite depletion in extracellular 

 fluid results. 



Diabetes is due primarily to faulty sugar metabolism, but it 

 is also constantly associated with those conditions that alleviate 

 epileptic convulsions such as ketosis, loss of water, and alkalinity. 

 The diabetic is exactly the reverse of the epileptic; he is dehy- 

 drated, while the epileptic is hydremic. Theoretically, a person 

 suffering from both epilepsy and diabetes should be extremely 

 rare; such is the case. 



Aging may in large measure be due to the inability of proto- 

 plasm to hold water, for as we grow old there is a decrease in 

 water content of the body. Attention has been called to this 

 under syneresis (page 146). 



Gortner has given special attention to the role of water in 

 plants, from the point of view of the state in which water exists 

 in the plant body, i.e., whether free or bound. By free water 

 is meant water in bulk. Bound water is water held to organic 

 substances by adsorptive or other forces. Only free water is 

 available for functions such as the translocation of food, the 

 photosynthesis of sugars, transpiration, sweating, the elimination 

 of toxic and waste products, etc. The chemical state of bound 

 water in the organism is not known. Even so old and familiar a 

 state as water of hydration is not understood fully. Bragg 

 believes that water of crystallization is so intimately bound to 

 the crystal molecule that it no longer exists as water but that, 



