Heredity 153 



/og = Class frequencies of total population in 1909. 



Fog = Value or measurement corresponding to a given 

 frequency in 1909. 



MW = Mean number of potatoes per hill in 1909. 



Dog = Deviation of number of tubers per hill from mean, 

 1909. 



cr 09 = Standard deviations of number of tubers per hill, 

 1909. 



/io = Class frequencies of total population in 1910. 



y 10 = Value or measurement corresponding to a given 

 frequency in 1910. 



MIQ = Mean number of potatoes per hill in 1910. 



DIO = Deviation of numbers of tubers per hill from 

 mean, 1910. 



o- 10 = Standard deviation of number of tubers per hill, 

 1910. 



r Coefficient of correlation. 



The process of finding the mean and standard devia- 

 tion is the same as is given in Chapter IV, so that the 

 only column that needs explanation is the one headed 

 SP. 



As an example, we will take the column on the 1910 

 tubers, beginning with 15.5. The figures 1, 1, 1, 1, 5, 

 9, 6, 5, 2, 3, 3, 1, 2, 1 are known as a horizontal array; 

 similarly the vertical columns are known as a vertical 

 array. We will now show how 535.01 in 3P column is 

 obtained. 



The first number after 15.5 is 1. Going down the verti- 

 cal column to column Di , we find 9.7, which is multi- 

 plied by 1 ; the same process is gone through for each 

 number following 15.5 and the algebraic sum is taken, 



