452 
Bulletin No. 161.—1914. 
on by a number of investigators, it can now be assumed safely that 
the factor for barring is inherited in a sex-limited manner; that is, 
the character can be transmitted by the males to both male and female 
progeny, but the barred females are unable to transmit the pattern 
to their daughters. 
Upon the basis of the assumptions mentioned above, and assuming 
furthermore, that the factor C embodies all that is necessary (in the 
absence of I) for black pigmentation, the zygotic formula of the White 
Leghorn cT may be written 
C' 2 B 2 f 2 I 2 
and that of the White Leghorn 9 as 
C 2 BbFfI 2 . 
On similar grounds the White Plymouth Rock cf, lacking all 
pigmentation factors, would be 
c 2 B 2 f 2 i 2 
and the White Plymouth Rock 9 
c 2 BbFfi 2 . 
In case, however, we make the supposition that two distinct 
factors are required for black pigmentation, and that only one of 
these (X) is present in the White Leghorn, while the White Plymouth 
Rock contains the other (Y), the formula of the White Leghorn c? 
becomes 
B 2 f 2 l 2 X 2 y 2 
and the White Leghorn 9 
BbFfI 2 X 2 y 2 . 
In a similar manner the White Plymouth Rock cf would be 
represented 
B 2 f 2 i 2 x 2 A 2 
and the White Plymouth Rock 9 as 
Bl)Ffi 2 x 2 Y 2 . 
The point at issue therefore is this: Which zygotic formula for 
the White Leghorn a 71 (C 2 B 2 f 2 I 2 or B 2 f 2 I 2 X 2 y 2 ), and which formula 
