CHAPTER XXIV. 



Casting Off the Useless Organs. 



TOURING the thousand million years or thereabouts that 

 ^^^ life has been struggling from the first life cell to the 

 present forms, the earth has been subjected to many geo- 

 graphic and climatic changes. These changes raised moun- 

 tain ranges, submerged continents and turned tropical lands 

 into regions of ice. As a matter of self-preservation, the 

 existing types had to make adaptations in their forms and 

 habits to meet these changes or perish. Many fell by the 

 wayside and perished while others struggled on by adapting 

 their bodies and habits to meet these new conditions and 

 lived. These adaptations not only brought about changes 

 in the form and function of existing organs, but they created 

 new organs as well to meet the changing vicissitudes of life. 

 It required sons to make and change these organs and other 

 asons to destroy and throw them off. A complete nev/ diet 

 and a complete reversal of inherited instincts had to be sub- 

 stituted for the former ways of living. Nature never throws 

 off a completed structure if the structure can be put to some 

 useful purpose but when an organ has become outgrown and 

 useless, it is Nature's law that it shall be cast off. 



A consideration of the structure of animal forms brings 

 us to one of the most conclusive proofs that God's plan of 

 creation was the evolutionary plan. Man and all other ani- 

 mals contain, in addition to their useful organs, many rudi- 



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