BRACHYDACTYLY IN THE FOWL . 101 
The male (no. 8) differed from these hens in a considerable 
number of characteristics, for most of which he seems to have 
been heterozygous. His color was partly that of a barred 
Plymouth Rock, although hackle, saddle feathers, and_ tail 
contained much white and the breast was somewhat spotted. 
The comb was broad and long with irregular elevations and a 
flattened, truncated and slightly trifid posterior prolongation. 
It did not seem to be either typically ‘rose’ or ‘walnut’ although 
perhaps more closely approaching the latter. The tarsi were 
moderately booted (grade 2 in an arbitrary scheme adopted for 
purposes of this paper). Digit I on the left foot was partially 
doubled (grade 2) while on the right foot it was normal. Digits 
IV were short, giving an index of 89. At the time of the 
experiment this bird was in the last half of his third year of life- 
HEREDITY OF CHARACTERISTICS 
The heredity of the five outstanding characteristics, color. 
comb form, polydactyly, booting and brachydactyly may be 
briefly summarized. The first four of these have been subjected 
to careful study by Davenport (’06, ’09) and others. 
A. Color. All. chicks that hatched and all embryos that 
reached the stage for developing down were white, or white with 
occasional small dark spots. White was to have been expected 
in the offspring since the white of the Leghorn is a well known 
dominant character. 
B. Comb. According to the prevailing view as to the unit 
factors involved (Bateson, ’09) four types of comb should have 
occurred in equal numbers: walnut, rose, pea and single. These 
four types did occur, but since in the embryo and chick it is 
often difficult to differentiate with certainty between rose and 
walnut (of the type met in this experiment), pea and single, 
the four categories were grouped into two; broad combs and 
narrow combs. Of 172 chicks and late embryos, 88 had broad 
combs and 84 narrow, the expectation being 86 of each. This 
is very close to the Mendelian ratio. 
