EXPERIMENTAL EVOLUTION 



525 



departs from the average for 

 that character, the less fre- 

 quent is its 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 

 Qu6telet'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.) 



