66 FOOD REQUIREMENTS 



bacteria decompose the carbohydrates, one or more molecules of 

 water are taken up; when they synthesize, water is eliminated. 

 The hydrolysis of fats requires for every molecule three of water; 

 when they are synthesized from glycerin and fatty acids three 

 molecules are eliminated. The digestion of the proteins by bacteria 

 is usually hydrolysis in which a number of molecules of water are 

 caused to enter the large protein molecule, thus causing it to break 

 down into elementary diffusible foods. When the bacteria build 

 their own proteins from the peptones and amino-acids, it requires 

 that water be eliminated. Thus water plays an all-important part 

 in all bacterial syntheses and decompositions. 



Water accelerates or is essential in all reactions taking place in 

 the cell. It has a higher inductive capacity, or dielectric constant, 

 than any other liquid, except possibly hydrogen dioxid. "It is a 

 good insulator. It does not in itself, at ordinary temperatures, 

 conduct the current readily. In virtue of this property it happens 

 that when electrical disturbances occur in a cell they are not 

 instantly compensated, so that oppositely charged particles may 

 coexist in water. It is probably because of this property that 

 water forms such a good ionizing medium. At any rate, this 

 property may account for the undoubted fact, whatever explanation 

 we may choose to give of that fact, that substances dissolved in 

 water interact with greater ease and speed than when dissolved in 

 any other medium. It has the property then, so important for the 

 cell, of accelerating all kinds of chemical reaction. Thus hydro- 

 gen and oxygen will not unite, except at very high temperatures, 

 unless some water is present. Hydrochloric acid and sodium 

 hydrate react vigorously in the presence of water, but not when they 

 are quite dry. Chlorin and hydrogen do not form hydrochloric 

 acid, except at very high temperatures, unless water be present, and 

 everyone knows that the rusting of iron does not occur unless water 

 is there too. W r ater has, then, this fundamental property of 

 making reactions go on between bodies dissolved in it or wet by it. 

 This property is believed by many to be correlated with its ionizing 

 powers and with the fact that its solutions conduct electrical currents 

 more than those of any other solvent." 



Another very remarkable property of water is its power of solu- 

 tion. No other solvent surpasses it. All substances dissolve in it 

 to some extent. It is a solvent for salts, carbohydrates, proteins 

 and even for fats to some extent. This universal solvent power 

 has not yet been fully explained, but it is probable that it is cor- 

 related with, or due to, the extra valances on the oxygen atoms 

 which are perhaps able to unite with the extra valances on the dis- 

 solving molecules and thus to produce solution. But be the expla- 

 nation what it may, it is well known that its solvent action con- 

 tributes much to life. Bacteria are able to absorb their food only 



