VESTIGIAL ORGANS 

 By George Howard Parker 



Professor of Zoology, Harvard University 



The body of an animal, like a piece of machinery, is made 

 up of numerous parts that work together toward a common 

 end. In an animal these parts are the organs, and each 

 organ commonly has a definite use. Thus in man the eye, 

 the hand, and the heart are three organs, the first for vision, 

 the second for prehension, and the third for the propulsion 

 of the blood. As in the machine, so in the animal, some 

 parts are more important than others. 



Just as there may be superfluous wheels and belts in a 

 machine, so there may be organs in an animal that are not 

 essential. A man may lose an arm or a leg and still live. 

 Paired organs may be reduced by the removal of one. Thus 

 a surgeon does not hesitate to excise a kidney provided its 

 mate can be left intact. After such an operation the organ 

 left behind usually enlarges and acts for two. Some single 

 organs, such as the spleen, or even the stomach, may be 

 removed without causing death. After its removal the func- 

 tion it ordinarily performs is taken over by other organs, 

 and the life of the individual continues. 



But in addition to organs of the kind just described there 

 are others whose loss is followed by death. None of the 

 higher animals can survive the loss of the heart, and every 



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