CELL-LIFE AND CELL-MULTIPLICATION. 263 



same part to the adjacent nitrogenous compounds as these 

 play to the carbo-hydrates. If so, we see arising a stage 

 earlier that " general physiological method " illustrated in 

 § 23/. It was there pointed out that in animal organisms 

 the various structures are so arranged that evolution of a 

 small amount of energy in one, sets up evolution of a larger 

 amount of energy in another; and often this multiplied 

 energy undergoes a second multiplication of like kind. If 

 this view is tenable, we may now suspect that this method 

 displayed in the structures of the Metazoa was initiated in 

 the structures of the Protozoa, and consequently characterizes 

 those homologues of them which compose the Metazoa. 



When contemplated from the suggested point of view, 

 karyokinesis appears to be not wholly incomprehensible. 

 For if the chromatin yields the energy which initiates 

 changes throughout the rest of the cell, we may see why 

 there eventually arises a process for exact halving of the 

 chromatin in a mother-cell between two daughter-cells. To 

 make clear the reason, let us suppose the portioning out of 

 the chromatin leaves one of the two with a sensibly smaller 

 amount than the other. What must result? Its source of 

 activity being relatively less, its rate of growth and its 

 energy of action will be less. If a protozoon, the weaker 

 progeny arising by division of it will originate an inferior 

 stirp, unable to compete successfully with that arising from 

 the sister-cell endowed with a larger portion of chromatin. By 

 continual elimination of the varieties which produce unequal 

 halving, necessarily at a disadvantage if a moiety of their 

 members tend continually to disappear, there will be estab- 

 lished a variety in which the halving is exact: the character 

 of this variety being such that all its members aid the per- 

 manent multiplication of the species. If, again, the case is 

 that of a metazoon, there will be the same eventual result. 

 An animal or plant in which the chromatin is unequally 

 divided among the cells, must have tissues of uncertain 



formation. Assume that an organ has, by survival of the 

 18 



