MULTIPLE ALLELOMORPHS 209 
such that one affects one combination of parts, 
another a different combination, the results find a 
simple and consistent explanation. It may seem 
strange at first that a factor may make the cob red 
and not color the grain or husk, while another 
allelomorph may make the grain and husk red but 
not affect the cob color, but it is no more strange than 
that one factor determines one distribution of the 
pigment over the coat and even in each hair of the 
gray mouse and another one determines another 
distribution. . 
Equally striking is the series of forms of the grouse 
locust (Paratettix) that Nabours has recently studied. 
Nine true breeding forms that are found in nature 
were studied. They differ markedly in color pattern 
(Fig. 52) but each color pattern behaves as a unit in 
heredity. The hybrid is in a sense intermediate, the 
color characters of each parent being superimposed. 
In fact Nabours finds that simple inspection of the 
hybrid suffices to show which forms were its parents. 
In the germ cells of the hybrid the two parental color 
types segregate as units. The resulting F. types 
are in the 1:2:1lratio. It is obvious, since only two 
of the color types can exist'in the same individual, 
and since they separate in the germ cells, that the 
condition of multiple allelomorphism is fulfilled. 
All Nabour’s crosses relating to color pattern (with 
some possible exceptions) follow the plan just out- 
lined. The case at first sight appears unique in that 
the color pattern of each type is complex in the sense 
that different parts of the body are differently affected 
