78 



INHEBITANCE OF CHARACTERISTICS IN DOMESTIC FOWL. 



In mating the F^ generation with each other or with the White Leghorn 

 the result must vary with the gametic output of the hybrid, which is obviously 

 very different in different cases. A hen, of a Hght buff color spangled with 

 white spots and having a black tail, presumably formed gametes CJnWX, 

 CJnwX, CJNWX, CJNwX. Mated with the White Leghorn, CJNWx, 

 she produced 8 pure whites, 4 whites with some black and red, 2 buff and 

 white, and 3 black with trace of white. Expectation in 16 offspring would 

 be about 4 pure whites, 4 white mixed with pigment, 4 buffs with white 

 (and black?), and 4 blacks mixed with other colors. This is merely an 

 illustration of the way the confused combinations of colors become intel- 

 ligible, and even necessary on the factor hypothesis. 



6. BLACK COCHIN X BUFF COCHIN. 

 (Plate 10.) 



The factors involved in this cross seem to be CINz for the Black Cochin 

 (in which I stands for the Jungle pattern without any associated color 

 factor) and CjnX for the Buff Cochin, as before. The Fj generation has the 

 zygotic composition CJjNnXx, and the females are all black, except for a 

 variable amount of red on the hackle, and the males are black and red, 

 like Games. The Fj generation is remarkable. Since 3 factors are heterozy- 

 gous, there are 64 possible combinations and 27 differing ones. In table 63 

 is given a list of these different combinations and of the probable associated 

 somatic colors. The prefixed number indicates the frequency of each 

 combination. 



Table 63. 



Uniting the blacks and black-and-reds (since red appears only in one 

 sex and often not until late in life) we find the following relation between 

 the calculated and the observed proportions in 86 offspring: Calculated, 

 black 65, buff 16, white 5; observed, black 61, buff 17, white 8. 



In still another pen (848) the Fj hybrids were mated to a Buff Cochin. 

 Only 21 chicks were raised. Expectation is, black 10.4, buff 5.2, white 5.2. 

 Actually there were obtained, black 7, buff 10, white 4. Half of the cal- 

 culated blacks are really heterozygous in both black and buff; so expecta- 

 tion is a little uncertain, and probably should be given as something under 

 10.4. Also, on account of small numbers, a close agreement is not to be 

 expected; but calculation and observation are at least of the same order. 



