300 Dynamic Theory. 



mobile, and then tears it down and dissolves it. But usually, as a pre- 

 liminary to the dissolution of the individual body and as more or less 

 contributory to it, a portion of it containing the essential elements oi 

 the whole i's transferred to a safe place where it is caused to grow tc 

 maturity and reproduce its parent, thus insuring the perpetuity of the 



FIG. 127. 



FIG. 127. Diagram illustrating cell division. a.Chromatin, or essential elements ol 

 nucleus united in the left fig. and drawn apart in the right, in the formation of the 

 daughter. nuclei, c. The polar protoplasmic centers. &. Protoplasmic threads or fila* 

 ments, extending from a to c. (&. & T.from Boveri.) 



race. If vitality were an inherent quality of the organism we should 

 have a right to expect that the child would exactly resemble its parent. 

 But from the fact that the energies which assail the child are not oi 

 precisely the same vibratory rates and force as those which governed 

 the parent, the child differs from the parent ; and this difference accu- 

 mulating from generation to generation constitutes the evolution of ne\\ 

 species and races. Obviously, then, the conditions which evolve a ne\* 

 race are unfavorable for the perpetuation of an old one ; or, in other 

 words, unfavorable for its perpetuation, and the process of changing in- 

 dividuals from generation to generation effects the change of race. And 

 thus we see how the reproduction of new individuals involves the disso- 

 lution of old ones, and the evolution of new races involves the extinc- 

 tion of their predecessors. The answer, then, to the question why a 

 cell does not remain stationary when maturity is reached, is that the en- 

 ergy which built it will not let it alone. 



A great many skillful and patient observers have spent a great deal 

 of time in watching the formation of the two kinds of sexual elements 

 and their mode of union and development ; and they have also observed 

 the growth of the simple asexual organisms from the original asexuaJ 

 cells. These observers agree in the main as to the facts and processes, 

 but have not succeeded in framing a satisfactory theory to account for 

 them. Of the theories that have been framed no doubt several contain 

 some elements of the truth ; although it is not yet possible to work out 

 any theory in great detail. Those who have attributed the phenomena 

 to the activity of polar energy are certainly on the right track. No1 

 that there is an innate tendency in "vitalized matter "to " unfold, " oi 



