30 Life and Death, Heredity and Evolution 



indefinitely without mating, makes it probable that the ap- 

 pearances are correct, and that such organisms as bacteria 

 actually never mate. 



Does this confirm the theory of the "potential immortal- 

 ity" of these creatures? It apparently does, if we are to 

 take that expression in its broadest meaning. But the real 

 question underlying that phrase is this: Does the exercise 

 of the functions of life itself necessarily result in deteriora- 

 tion, in senility, in final death? This was the question that 

 Maupas believed his experiments to answer affirmatively. 

 He says of his experiments, "They demonstrate that indeed 

 in the ciliate infusoria, as in so many, if not all, other living 

 things, the organism deteriorates, uses itself up, simply by 

 the prolonged exercise of its functions" (1888, p. 261). 



The experiments we have described above show that con- 

 jugation is not required to remedy the wearing away of the 

 organism through the exercise of its vital functions. But 

 is this the complete story? Is there after all no significance 

 in the fact that these creatures keep a reserve nucleus, along 

 with the active one? Does the active nucleus never require 

 replacement from the reserve? 



This question too has recently been answered, mainly by 

 the work of Woodruff and Erdmann (1914). And in an- 

 swering the question they have succeeded in observing that 

 separation of the two processes in conjugation, of which 

 we said above there was so much need. These two processes 

 are: first, the replacement of the active nucleus from the 

 reserve ; second, the exchange of parts of the nuclei in 

 mating. Woodruff and Erdmann observed the replacement 

 process occurring without mating and exchange. And in 

 doing this they have uncovered what is evidently one of the 

 most important phenomena that occur in the life of these 

 Protozoa; something that must form a background for all 



