348 



THE WHEAT PLANT 



Similarly, the number of spikelets per ear varied between 14 and 24, 

 and the number of internodes per straw between 4 and 7, with the 

 following frequency distributions : 



NUMBER OF SPIKELETS PER EAR 



NUMBER OF INTERNODES PER STRAW 



In dealing with quantitative variations the application of statistical 

 methods is of great service in obtaining accurate expressions for the 

 amount and range of the variability of each character, and the determina- 

 tion of the mean (M), the standard deviation (<r), and the coefficient of 

 variability (C), or ratio of the standard deviation to the mean of all 

 fluctuating characters of plants, the pedigree of which is known, would 

 be of much value. 



Some of these, obtained <from investigations of " Swan " wheat, are 

 given below : 



The following results obtained by Oetken refer to a Squarehead 

 wheat : 



