EVOLUTION AND HUMAN DESTINY 



process does in no way invalidate the argument pur- 

 sued in this chapter. 



The bifurcation between the animal and plant 

 branches of life occurred at an evolutionary stage below 

 the development of more complex protozoa. It seems 

 therefore highly probable that both branches of life 

 independently evolved the cell fusion method of 

 reproduction. It is equally significant that the inevi- 

 tability of death for the individual, but the preserva- 

 tion of the species, holds equally for plants as well as 

 for animals. 



DEATH IN METAZOA 



The method of reproduction found in the higher 

 multicellular animals as well as in the higher plants 

 depends clearly upon the mechanism of cell fusion. 

 The cells that fuse of course are then no longer cells 

 which act as both somatic and genetic cells at the same 

 time, but are highly specialized genetic cells, the com- 

 plex structure of which carries the code of organization 

 of the entire individual. The situation will be consid- 

 ered again later when we shall discuss the nature of 

 the multicellular organisms (metazoa) . 



In complex higher animals and plants, the cause of 

 aging and natural death need of course not be the 

 accumulated mutation damage in all the tissue. As 

 has been pointed out, different types of cells vary in 

 their resistance to mutation damage. So at the time a 



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