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HEREDITY 



11 



senting the distribution of variation is to take a base- 

 line and divide it into equal parts, each representing 

 an equal increment in the structure measured. From 

 each division of the base-line a vertical line is drawn 

 representing by its length the number of individuals 

 having that measurement. 



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300 400 500 COO 700 800 SOO 1000 



Fig. 1. Carve illustrating stature, the vertical scale representing 

 heights above 60 inches, the horizontal scale numbers of indi- 

 viduals (up to 1000). 



In the imaginary case taken above, the base-line 

 would have 17 divisions representing successive 

 heights of from 60 to 76 inches ; at each division 

 a vertical line is drawn which by its length repre- 

 sents the percentage of the population which have 

 that height (fig. 2). By joining the tops of the per- 

 pendiculars (ordinates) a curve, or more strictly a 

 polygon, is obtained which graphically represents the 



