102 BIOMETRY 



of the sons. And the separation into two groups was 

 made in several different ways by taking the dividing 

 line between the groups at various heights. By 

 applying to the statistics disposed in these various 

 arrangements the same method as was applied to the 

 statistics of horse colour already referred to, values 

 varying between 0-52 and 0*6 were obtained for 

 parental correlation ; whereas the value arrived at by 

 the more usual and reliable method was 0*514. It 

 would therefore appear that there is with this method 

 a tendency to obtain too high a figure, as compared with 

 that derived from the method of the complete correla- 

 tion table. When this source of inaccuracy is taken 

 into consideration, in combination with the doubtful- 

 ness of the assumption upon which the method is 

 based, it seems clear that its use will only give us a 

 roughly approximate view of the correlation actually 

 existing in the cases to which it is applied. Having 

 made this reservation, we may compare the values 

 given in the following table with those which appeared 

 in Table V. : 



TABLE VI. (FROM PEARSON). 



AVERAGE PARENTAL CORRELATION. 



Human eye colour ... ... ... 0-495 



Horse, coat colour ... ... ... 0-522 



Basset hound, coat colour ... ... 0^524 



Greyhound, coat colour ... ... 0*507 



AVERAGE FRATERNAL CORRELATION. 



Human eye colour ... . . 0*475 



Horse, coat colour ... . . 0*633 



Basset hound, coat colour . . 0*524 



Greyhound, red in coat . . 0700 



Greyhound, black in coat . . 0*660 



