LIFE AND DEATH 



HEREDITY AND EVOLUTION IN 

 UNICELLULAR ORGANISMS 



General Survey of the Life History in the Protozoa, with 

 the Questions it Raises. Life, Death, Reproduction, Mating, 

 Rejuvenescence, "Potential Immortality." 



LONG ago, when Latin was the common language of 

 science, there was current a saying that nature is 

 greatest in the things that are smallest : Natura mamma in 

 minimis. Radl, in his History of Biological Theories, cites 

 this as a maxim which led to mere superficiality ; to the 

 degeneration of biology toward an amusement, with the 

 microscope as its instrument ; to neglect of the really great 

 problems of life. The nai've literature of the old fashioned 

 microscopical societies, with their talk of the "golden tube," 

 and of the "Oh, my! objects," passed from one member to 

 another for the consecutive delectation of their eyes, lends 

 some plausibility to this indictment ; even yet the drama 

 of life seen in a drop of water has its purely aesthetic fasci- 

 nation. But such fascination is not inevitably inconsistent 

 with a serious value for studies of these creatures ; there 

 still exist students who, in spite of Radl's sarcasm, believe 

 that the simpler creatures have something to teach us on 

 even the deepest problems of life. I am going to try to 



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