390 



CHARLES It. STOCKARD 



suiting from combinations of the pure recessive ss for short 

 and the dominant St for straight, but the short tail is straight 

 only when homozygous for straight, StSt; when pure for 

 short and heterozygous for straight, Stb, the short tail shows 

 a simple bend. Therefore, in the F 2 generation only one tail 

 in sixteen, instead of three in sixteen, is short and straight. 



L-St 



s-St 



L-b 



s-b 



L-St ' s-St 



s-b 



LL-StSt 



Ls-StSt 



LL-Stb 



Ls-Stb 



L s-St St 



s s-St St 



Ls-Stb 



ss-Stb 



LL-Stb 



Ls-Stb 



LL-bb 



Ls-bb 



Ls-Stb 



s s-Stb 



Ls-bb 



ss-bb 



Text-figure 78. Diagram showing the sixteen possible genie combinations for 

 t.-iil length and structure in second generation bulldog-bassethound hybrids. L, 

 long; St, straight; s, short; b, bent. 



Iii combination with the homozygous allels for short, ss, 

 straight is not fully dominant over bent, but it is completely 

 dominant over bent in the long tail, as is shown by the 

 sea icily of Long-bent tails among more than 150 F2 hybrids, 

 and by the complete absence of bent tails among the F x 



