434 TRANSMISSION 



with that of any other race, plant or animal, and for any charac- 

 ter of which accurate measurements can be taken and a fre- 

 quency distribution be constructed. 1 



Practical application of the coefficient of variability. The 

 value of this term lies in the fact that it affords an accurate 

 means of comparing directly the variability of one frequency 

 distribution with that of another, no matter what the character, - 

 whether in the same or different individuals, or between similar 

 or unlike species. Thus, by this means we may compare the vari- 

 ability of the length of an ear of corn with that of its weight ; 

 the variability of its circumference with, that of its number of 

 rows, or with that of any other measurable character. 



We can also, in this way, compare the variability of ears of 

 corn with that of their stalks ; with that of the length of horse's 

 legs, of what they can pull, or of the rate at which they can 

 travel ; with that of the height of men, their weight, length of 

 arms, measurements of the head, indeed, with that of any 

 object, living or non-living, that possesses variable characters 

 that can be accurately measured, whether by feet, inches, 

 pounds, or by any other unit that can be devised. 2 



By means of this coefficient the breeder may not only ascertain 

 whether one character is more variable than another, but by 

 taking this coefficient frequently, as annually for the same variety 

 or under different conditions, he can know the variability of the 

 same character as influenced by time or circumstances. 



In general these determinations enable the breeder to know 

 which way his varieties are drifting, or whether they are standing 



1 Clearly, if the mode or the standard of selection has been used as a base in 

 calculating the deviation, then the same value should be used as a base in calcu- 

 lating the coefficient ; thus it is possible to secure a coefficient of variability from 

 any desired type as well as from the mean. 



2 The coefficient of variability has been worked out for a large number of 

 characters in man, as is shown in the following table (see Vernon, Variation in 

 Animals and Plants, p. 24). 



Nose length 9.49 Head breadth 2.78 



Nose breadth 7.57 Upper arm length 6.50 



Nose height 15.20 Forearm length 3.85 



Forehead height 10.40 Upper leg length 5.00 



Under jaw length 4.81 Lower leg length 5.04 



Mouth breadth 5.18 Foot length 5.92 



Head length 2.44 



