EVOLUTION— ITS MEANING 



other trustees which will carry that organization on and 

 into the future." ^ 



The reahty of evolution in organic life once admitted, the 

 next step must be to trace the details of its operation. For 

 we recognize no "law of evolution" as working without 

 regard to conditions. Evolution in vacuo is a philosophic 

 fancy. Conclusions resting on analogies, or on the juggling 

 of words, are not a part of science. "Living organisms," 

 says Dr. Osborn, "differ from lifeless mechanisms, no matter 

 how perfect, in being more or less self-adapting, self-reform- 

 ing, self-perfecting, self-regenerating, self-modifying, self- 

 resourceful, self-experimental, self -creative." In other words, 

 they possess — 



Individuality: No two organisms are exactly alike. 



Irritability: The response to external stimulus, every 

 organism being either swayed by influences bearing 

 upon it or else reacting against them. Through 

 evolution this response rises by degrees to tropism 

 — the tendency to react in a definite manner — and 

 to reflex action, with its specialized derivatives, 

 instinct and intelligence. 



Reproduction: The casting off of specialized cells, 

 each one of which (usually united with its mate 

 through amphimixis) initiates a new individual. 



Metabolism: The wearing away of tissues and their 

 replenishment by food derived from the substance of 

 other organisms, or from water and from air. 



Growth: The development in size and in specializa- 

 tion of the fertilized cell, which is followed by dete- 

 rioration and death, except in one-celled organisms, 

 where we have cell division instead of death. 



^ Calkins, G. N. 



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