242 



Biology in America 



characters (weight, length, etc.) center around a new mode 

 which is higher or lower than the original. If the character 



180 



/to 



/to 



loo 



60 



15 6 /S3 161 166 /66 /?/ /71 /71 16O /83 /06 /Q3 f9Z &f/98 



FREQUENCY-POLYGON AND CURVE 



Showing variation in height of one thousand Harvard students of 

 ages 18-25. Number of individuals shown by ordinates, and heights 

 (in centimeters) by abscissae. After Castle, " Genetics and Eugenics." 

 By permission of Harvard University Press. 



of each of these groups be plotted, a series of curves is ob- 

 tained, each of which represents " fluctuating" variability of 

 the smaller group and has its own mode. If all of these 



