346 BIOLOGY 



made for those localities, since in many cases they are better 

 fitted for other localities than their own homes. The idea that 

 organisms were especially designed by creation to fit the con- 

 ditions in which they live is thus disproved. 



Adaptation the Result of Growth. The history of organisms 

 shows that adaptation to environment has not come suddenly, 

 but has been the result of slow development, brought about by 

 race divergence and evolution. 



Adaptation in the life of the individual. When the individual 

 starts its existence it is simply a fertilized egg. It is a cell, and 

 is not especially adapted to any particular condition of life. 

 In its development the cell divides into many cells, and these 

 cells assume different shapes and relations. As the organism 

 grows, the adaptation to the environment makes its appearance. 

 In plants, the roots soon assume a form which adapts them to 

 the soil, while the leaves become fitted for the air; in animals, 

 some cells adapt themselves to functions of digestion, others 

 to the functions of motion, etc. In other words, in the life of 

 the individual, adaptation is a matter of slow growth and comes 

 step by step as the egg is gradually molding itself, into the form 

 of the adult. Concealed in this fertilized egg are marvelous 

 powers which cause the egg to develop into an adult, and the 

 powers that cause the development of the egg cause also the 

 adaptation of the different parts to the conditions of life. 



Adaptation in the race. There is no doubt that a similar 

 history of growth has brought about the adaptation of the race 

 to environment. Probably the earliest type of the plant was a 

 single cell, adapted to life in the water but not in the soil. As 

 the ages passed on and plants reached the land, an adaptation 

 to this new environment slowly developed. The structures 

 which we find in animals and plants to-day, which adapt them 

 to their environment, were not of sudden origin in any case, 

 but were the result of a gradual change of the older forms into 

 newer types, more closely adapted to the new conditions of life. 



As an example of such adaptation, may be mentioned the 



