viii.] DISCUSSION OF THE DATA OF EYE COLOUR. 151 



respectively. Hence the aggregate of the probable 

 heritages from G x are expressed by the following 

 series : — 



d/-x -+1 xl+-x 2 x~+-x 4 xi+&c. ) 



\3 2 2 2 J 3 2° 9 2 s j 



= b\1 +(L+_J_+ * + &c )1 = D x(^ + -V D xO-16. 

 Il2 V2 4 3x2 5 3 2 x2 15 Ji U2 40/ 



So that each grandparent contributes on the average 

 0"16 (more exactly 0*1 583) of his peculiarity to the 

 heritage of S, and the four grandparents contribute 

 between them 0"64, leaving 36 indeterminate, which 

 when rateably assigned gives 0*25 to light and O'll 

 to dark. A hazel-eyed grandparent contributes, accord- 

 ing to the ratio described in the last paragraph, 

 0*10 to light and 0'06 to dark. All this is clearly 

 expressed and employed in the columns II. of Tables 17 

 and 18. 



III. Eye- colours given of the two Parents and four 

 Grand-Parents — 



Suppose F to possess D, then F taken alone., and not 

 in connection with what his possession of D might imply 

 concerning the contributions of the previous ancestry, 

 will contribute an average of 0'25 to the heritage of 

 S„ Suppose G x also to possess D, then his contribution 

 together with what his possession of D may imply 

 concerning the previous ancestry, was calculated in the 

 last paragraph as D x ^ 3 F = D x 0*075. For the con- 

 venience of using round numbers I take this as 

 Dx0'08. So the two parents contribute between 



