152 GENETICS IN RELATION TO AGRICULTURE 
the quantitative relations obtaining in the determination of dominance. 
Apparently the relations are about the same as those shown in the case 
of bar eye in Drosophila, for conceivably, if such a thing could be obtained, 
an endosperm arising from an Ff cell might show the same variation 
between flinty and floury that is shown in the bar-eye character of flies 
of the genetic constitution (B’X) (b’X). 
Mosaic Expression of the Hybrid Character.—Another type of hybrid 
condition is that in which the Aa individuals are a mosaic of the char- 
acters of the two parents. This condition is very strikingly illustrated 
in Blue Andalusian fowls. Andalusian fowls are of three types: 
black, splashed white, and the so-called blue. Of these types the black 
and splashed white breed true, but the blue is a hybrid and constantly 
segregates in the ratio Lblack: 2blue:1splashed white. When 
black and splashed white are mated, the progeny are all blue. The 
Blue Andalusian fowl of the Poultry Standard of Perfection is, there- 
fore, a heterozygous form and for that reason all attempts to establish 
it as a pure breeding race have failed. The case, however, is of interest 
here because the Blue Andalusian is a peculiar mosaic of the characters 
exhibited by the black and splashed white. Its “blue” color is simply 
due to a fine but uneven sprinkling of black pigment through the 
feathers; and on some portions as for instance the feathers of the breast, 
the black is present as a distinct edging or lacing of the feathers. 
Similar mosiac hybrids which represent a simple heterozygous con- 
dition have been reported by Nabours in grouse locusts of the genus 
Parattetix. Nabours found nine distinct races which bred true for 
particular color patterns. Hybrids, however, between any two of these 
species display the entire color pattern of both parents, the color patterns 
being merely superimposed one upon another and in such a manner that 
the entire pigmentation of both parents is present in the hybrid and is 
distributed in the same fashion. If then two races of Parattetix A and 
B be crossed, the hybrid AB will be a mosiac of the two parents, and it is 
possible by simple inspection of such a hybrid form to determine what 
races entered into it. Such a hybrid will give a population consisting 
of 14:24B:1B, thus demonstrating that the case rests on a simple 
factor basis and that the mosaic pattern is simply an expression of a 
heterozygous condition in which both A and a, if we designate them thus, 
work out their full possibility in the development of the hybrid. In 
certain cases which did not appear to conform to this simple interpreta- 
tion, a microscopic examination was resorted to. This examination dem- 
onstrated that the lack of agreement was apparent rather than real. 
Thus in Fig. 72 the superficial characters of the hybrid (BI) between P. 
leuconotus (BB) and P. nigronotatus (II) are for the most part those of P. 
leuconotus except for the broad black band across the pronotum which is 
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