PROBLEMS OF 

 ORGANIC ADAPTATION 1 



LECTURE I 

 FITNESS IN THE LIVING WORLD 



A DAPTABILITY may be defined as the power of self- 

 <L\. regulation, self-preservation, and race perpetuation, by 

 means of which living things are enabled not only to remain 

 alive but also to adjust themselves to varied environmental 

 conditions and to leave offspring. From the standpoint of 

 any species the best that can happen is to increase and multi- 

 ply, the worst is to become extinct. Self-preservation and 

 race perpetuation are the summum bonum; everything that 

 makes for these is beneficial and adaptive, everything that 

 prevents or hinders these is injurious or unfit. Adaptability 

 is a fundamental property of living things without which life 

 itself could not long persist, for as Herbert Spencer has said, 

 life is "continuous adjustment of internal relations to ex- 

 ternal relations." The origin of this or of any other funda- 

 mental property of life, such as metabolism, reproduction, 

 or irritability, is shrouded in the same mystery as the origin 

 of life itself. 



On the other hand, adaptations are special adjustments 

 to particular conditions; they are indvidual examples of the 

 general property of adaptability. As such they have arisen 

 in the course of organic evolution, and their origin, no less 

 than other special structures and functions, must be ex- 

 plained by any adequate theory of evolution. 



X A course of three public lectures delivered at the Rice Institute, March 

 8, 9, and 10, 1921, by Edwin Grant Conklin, Ph.D. (Johns Hopkins), Profes- 

 sor of Biology in Princeton University. 



