294 Shnll. 



(6) yO =3, yy = cT (Gulick 1911, Hertwig 1912). 



(7) zO = 9, zz = cT (Hertwig 1912). 



5. The male is assumed to be a negative homozygote. 



Model formulae: XXFf = 9, XXff= d", 



or simply, J?Jf = 9, ff= cT. 



These formulae have been used by SPILLMAN (1908), GOODALE 



(1909), HUEST (1909), PEARL and SURFACE (I910a,b), MOEGAN (1911a), 



BATESON and PUNNETT (1911), COLE (1912), MOEGAN and GOODALE 



(1912), HADLEY (1913), GOLDSCHMIDT (1913), and JOHANNSEN (1913). 



Synonymous formulae: 



(1) Ffmm = 9, ffinm = <? (Morgan 1911a). 



(2) FO = 9, 00 = cf (Morgan 1911 a, Morgan and 



Goodale 1912). 



(3) FG = 9, GG = c? (Wilson 1910, Pinney 1911). 



(4) X =9, no-X = cT (Castle 1909). 



(5) X - =9, = c? (Castle 1912). 



(6) XO = 9, 00 = <? (Morgan 1911 a). 



(7) xO = 9, 00 =<? (Hertwig 1912). 



(8) XO =9,0 '= oT (Pinney 1911). 



(9) XY = 9, YY =tf (Wilson 1910, Morgan and 



Goodale 1912). 

 (10) xy = 9, yy = cT (Schleip 1912). 



6. TAe mate is assumed to be a neutral homozygote. 



Model formulae: XXFM = 9, XXM M = J, 



or simply, FM = 9, MM = <?. 

 These formulae have been used by FEDEELEY (1911). 

 Synonymous formulae: 



(1) f(m) = 9, mm = d" (Schleip 1912). 



(2) 9d" = 9, cTcT = cT (Punnett and Bateson 1908, 



Doncaster 1908, Bateson 1909, Hurst 

 1909, Goodale 1910, Smith 1910, 1911, 

 1913, Morgan 1911 a). 



(3) 9(cT) = 9, dV = d 71 (Wilson 1909). 



The 50 sets of formulae here listed are not all that have been 

 used to represent these 6 fundamentally distinct ideas regarding the 

 genotypic interrelations of the sexes, but they are sufficient, I think, 

 to indicate the degree of simplification which would result from a general 



