ORGANIZATION AND VITALITY 111 



entirely ignorant. Through observation it has been determined 

 that practically each of the essential protoplasmic constituents 

 divides — plastids, chromatin granules, kinetic elements, nucleus, 

 and finally the cell as a whole. Metaplastids, reserve granules, 

 and in general, structures of the derived organization, do not 

 divide, but are either passively distributed to the daughter cells 

 or are absorbed into the protoplasm to be replaced later through 

 the metabolic activities of the young cells. 



Cell division is thus a complicated and deeply seated series 

 of phenomena in the life of the organism, and results in a gen- 

 eral housecleaning and restoration of the fundamental proto- 

 plasmic organization. Endomixis (see page 87) usually accom- 

 panied by encystment, has a similar but more far-reaching effect, 

 for the cytoplasm is thereby restored with nucleo-proteins and 

 the "nuclear apparatus is renewed. In both cell division and en- 

 domixis the result is restoration of vitality through reorganiza- 

 tion of protoplasmic materials. 



It would seem that this cycle of metabolic activities and 

 periodic reorganization should be adequate to maintain a pro- 

 tozoan through an indefinitely continued existence in a suitable 

 environment. Such indeed was the conclusion expressed by the 

 German biologist, August Weismann, in his essays on life and 

 death written in 1880-1882, in which he argued that protozoa 

 are potentially immortal and that natural death is the penalty 

 which metazoa have to pay for their differentiation into somatic* 

 and germinal t protoplasm. This idea is apparently borne out 

 by the cultivation by the German biologist, Max Hartmann 

 (1876- ) of the phytoflagellate, Eudorina elegans, for a 



period of fifteen years without fertilization, or endomictic proc- 

 esses — division and reorganization alone being adequate for 

 continued vitality. Similar evidence is furnished by the ten- 

 year culture by the German biologist, Karl I. Belar ( 1895-1931 ) , 

 of the protoplasm of Actinophrys sol, a heliozoan, without fer- 

 tilization and without diminution of vitality. Still further evi- 

 dence is furnished by the continued life of all animal flagellates 

 where no sexual or fertilization phenomena are known. 



* Somatic protoplasm in metazoa, those cells of the body of an individual which 

 compose the tissues, organs, and parts of that individual ; these are the cells which 

 die and cause the death of the individual. 



t Germinal protoplasm, the germ cells, which may live and carry on the race. 



