246 EVOLUTION AND GENETICS 



more evidently adaptive characters in the latter category have 

 been classified in detail. They include adaptations for aquatic 

 and terrestrial life and for flight, adaptations to varying degrees 

 of moisture and light, and adaptations for association with other 

 organisms. Organic relations necessitate special structures for 

 securing food and for protection. Protective adaptations are 

 exceedingly varied, including structural adaptations for speed and 

 many other characters. Both ends are gained by more or less 

 permanent associations of animals and by coloration and mimicry. 

 The idea of the web of life expresses the complexity of organic 

 relationships from which is derived much of the subject-matter 

 of evolution. 



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Roosevelt, T., African Game Trails, Appendix E, 1910. 



Wheeler, W. M., Ants, 1910. 



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