EXPERIMENTAL EVOLUTION 



525 



departs from the average for 

 that character, the less fre- 

 quent is Us occurrence. 



In another experiment, 

 ears of corn, harvested from 

 the same crop, were meas- 

 ured and found to vary 

 in length from 4)^ inches 

 to 9 inches; the largest num- 

 ber of ears (20) were 7 

 inches long. The greater 

 the departure from this 

 length, in either direction, 

 the fewer the individuals; 

 for the lengths 4 inches and 



FIG. 392. Demonstration of 

 Quetelet's law of fluctuating varia- 

 bility in the length of seeds of the 

 common bean (Phaseolus vulgaris) . 

 Description in the text. (Redrawn 

 from de Vries.) 



FIG. 393. Curve of fluctuating variation (Quetelet's curve), formed by 

 arranging 82 ears of corn in ten piles, according to the length of the ears. 

 The extremes were 4.5 and 9 inches. The ears were taken from unselected 

 material from a field of corn. (After Blakeslee.) 



