38 



INHERITANCE OF CHARACTERISTICS IN DOMESTIC FOWL. 



In 25 cases of the 52 an oil-gland was looked for and, in every case, 

 it was found to be missing. 



Table 26, the conclusions from which were drawn in my 1906 report, 

 seemed to indicate the dominance of tail over its absence. On this 

 hypothesis I suspected that if No. 117 were bred to his (tailed) offspring 

 about 50 per cent of the progeny would be taiUess, and if the tailed hybrids 

 of the F, were bred together about 25 per cent of their progeny should 

 be tailless. The actual result of such matings is shown in table 27. 



Table 27. — Heterozygotes mated withfaiher. 



The results given in tables 27 and 28 are remarkable. Neither in the 

 DR X E, nor the DR X DR crosses did the tail fail to develop. The tailless 

 condition, that I had strongly suspected of being recessive and expected 

 in 25 per cent to 50 per cent of the offspring, never once appeared. The 

 only point of variation in the uropygium of the chicks derived from the 

 back cross or from F/s bred inter se was that in some the uropygium seemed 

 distinctly smaller than in the others. This smaU uropygium was as a matter 



