No. 589] SHORTER ARTICLES AND DISCUSSION 



47 



recessive type, in contradistinction to spotting of the dominant 

 type described by Miss Durham ( '08). Through the kindness of 

 Professor W. E. Castle, a black-eyed white male was received in 

 the fall of 1914. With this male it was possible to produce other 

 black-eyed whites. In such black-eyed whites as I have been 

 able to test, both dominant and recessive spotting were present. 

 Furthermore, the recessive spotting always occurred in double 

 dose. Hence, black-eyed whites were supposed to have the zy- 

 gotic formula PPss or Ppss. in which P stands for dominant spot- 

 ting and p for its absence ; and s represents the factor for reces- 

 sive spotting winch is allelomorphic to self (S). So far, I have 

 been able to test sufficiently only two black-eyed white males, botn 

 of which were clearly of the formula Ppss. When mated to self- 

 colored females they gave 231 offspring. Since these offspring 

 showed much variability, they were graded in classes ranging 

 from self (—9) to black-eyed white (+9) according to the 

 amount of pigmentation which they showed. A distinct group- 



About one-half of the Pj offspring was grouped around the lower 

 mode (126), and the other half (105) grouped around the upper 

 mode, if we assume the class — 7, as the dividing class. Very 

 few individuals were found in the "doubtful class." Expressing 

 the cross of black-eyed white with self-colored in Mendelian 

 terms, it would be : 



Ppss X ppSS = P t zygotes 

 Ps + ps = gametes of black-eyed white P, 

 PS+ PS = gametes of self-colored P, 

 PpSs-f p P Ss=F 1 zygotes 

 Spotted + Self 



The results conformed to this expectation. The individuals 

 grouped around the lower mode were self-colored or very nearly 



recessive spotting, for self is dominant or very nearly dominant 

 to recessive spotting. Their formula was ppSs. Subsequent 

 experiments corroborated this, for they produced self and reces- 

 sive spotted in Mendelian ratios, when mated inter se or to reces- 



