250 



HEREDITY AND VARIATION 



but that he would tell me that he resembled in many respects his 

 mother or father. Likewise if I should ask his parents whom he 

 resembled, they would say, " I can see his grandmother or his 

 grandfather in him." 



This wonderful force which causes the likeness of the child to 

 its parents and to their parents we call heredity. Heredit}^ causes 

 the plants as well as animals to be like their parents. If we 

 trace the workings of heredity in our own individual case, we will 

 probably find that we are molded like our ancestors not only in 

 physical characteristics but in mental qualities as well. The 

 ability to play the piano or to paint is probably as much a case of 

 inheritance as the color of our eyes or the shape of our nose. We 

 are a complex of physical and mental characters, received in part 

 from all our ancestors. 



Variation. But I notice another thing ; no boy in the class 

 before me is exactly like any other boy, even twins having minute 

 differences. In this wonderful mold of nature each one of us 



Variations in the Catalpa caterpillar. (Photographed, natural size, 

 by Davison.) 



