-] Organic Physi 



475 



In fact there could be no other if this growth be a chemical pro- 

 cess, for synthesis is a self-checking method and cannot long con- 

 tinue unless its energy be restored by analysis. If a mass of 

 protoplasm be made up of molecules of the same chemical consti- 

 tution they may yet differ in degree of satisfaction of their affini- 

 ties, and may be partly neutral, partly basic, and partly acid in 

 their energies. Any exercise of these affinities tends to reduce 

 them all to neutrality, and thus to restrict their chemical action. 

 But they are constantly exposed to the assaults of oxygen, which, 

 at every contact, robs them of some of their constituents, and thus 

 restores their chemical activity. We must certainly deduce some 

 such conclusion as this from the necessity of oxygen to all life 

 energy, and the increase in oxidized waste with every increase in 

 vital activity. Oxidation gives rise to this vital activity, which con- 

 sists in the restoration of active chemical affinity to the oxidized 

 molecules, and in the reproduction of protoplasmic tissues. Both 

 results arise from one cause. Oxygen robs matter from the pro- 

 teid molecules, and restores their lost chemical energy. They 

 assimilate new material from the nutrient fluid; while animal 

 motion and temperature arise from the excess of energy yielded 

 by the oxidation. 



This general survey of the process leads us to a more particu- 

 lar conception of its character. There is a peculiar polarity con- 

 cerned in all chemical processes which is of essential importance 

 here. A neutral salt is really a polar arrangement of the ele- 

 ments. Its molecule has its positive and negative poles, but the 

 energy of each restrains and balances that of the other. If we call 

 such a molecule an acid salt, this is equivalent to saying that its 

 acid pole has an excess of energy over its basic. New basic ma- 

 terial is drawn in, and the poles become equal in energy, so that 

 all their affinities are exercised internally. But if the constituents 

 °f this molecule be separated, their opposite chemical polarities at 

 °nce become active. The one becomes an energetic base, the 

 other an energetic acid. If this separation proceeds further, a 

 portion of the products of the second separation becomes still 

 m ore powerfully basic or acid, while other portions may return 

 towards neutrality. If, for illustration, we take a molecule of the 

 Powerful acid H. 2 S0 4 and cause it to combine with two mole- 

 cules of the equally powerful base NaOH, we obtain the neutral 

 salt Na SO, two molecules of water being ejected. A redi vision 



