4 8o Organic Physics. [June, 



It might seem as if in such a process we had a provision for an 

 endless life activity. The chemical energy of protoplasm, con- 

 stantly quickened as it is by oxidation, appears capable of yielding 

 an indefinitely large mass of material, so that the bulk and length 

 of life of organisms might have no limits. Yet we are well aware 

 that no such results take place, and therefore must believe that they 

 are impossible. There must be some principle that checks both 

 an indefinite increase in bulk and a ceaseless continuance of life. 



There is such a principle, and the first step of its action is a 

 check to indefinite growth of the nuclear unit. For the activity 

 of this growth free access both of nutriment and of oxygen is 

 necessary. But the oxidation to which growth is due quickly 

 interposes a check to its activity. Some of the waste materials 

 yielded by oxidation appear to remain within the nucleus. Others 

 collect around it and form a mass which is known as the organic 

 cell, of which the nucleus occupies the center. Evidently this 

 process must oppose that of nuclear growth. With every exer- 

 cise of chemical activity the mass of " formed material " around 

 the nucleus increases in bulk, the access of oxygen and of nutri- 

 ment is more and more hindered, and the nuclear energy is 



There is only one method by which it can be regained. The 

 waste material continues to cling firmly around it, and only by 

 division of the mass into smaller portions can its nuclear center 

 regain its former relations with the nutriment. This division 

 takes place, and always through the nucleus. It might be imag- 

 ined, indeed, that a vigorous effort was made by the polar con- 

 stituents of the nucleus to reach the attractive nutriment, since 

 division, is always preceded by a strongly declared polar arrange- 

 ment of its material, and it separates at its equator, its two origin* 

 poles becoming the nuclear centers of two new cells. Growth 

 energy is regained in these new cells, but its vigor is decreased 

 with every successive division, for a reason now to be given. 



