No. 595] 



LINKAGE INTENSITIES 



413 



denoting dominance— and if 2n equal the sum of the 

 gametic series, 2 then the gametic series and the pheno- 

 typic zygotic series, AB, Ab, aB, ab, for coupling and for 

 repulsion are: 



2— (2n — 1) : 2n— 1: 



That is, the formulae of Bateson and Punnett are ex- 

 pressed in terms of the sum of the gametic series. But 

 the same thing can also be expressed in terms of the 

 several members of the gametic series. Thus, if r:s : 

 any gametic ratio, the usual form of gametic series : 

 r:s:s:r and the frequencies of the ten possible genotyp: 

 classes and of the corresponding four phenotypic classes 



The general formula for calculating a phenotypic 

 ygotic series from a given gametic ratio is, therefore, 

 3 f 2 + 9( S 2 + 2rs) : s 2 + 2rs : 5 2 + 2rs : r 2 (I) 



The s 



(2r + 2, 



sygotic series is 4r- -f- ors - 



len expressed as 



-s + r)(r + s +s + s + r), 



