HEREDITY IN PLANTS, ANIMALS, AND MAN. 371 
which have been obtained in the experiments. The colour factor is indi- 
cated by ©, the absence of this factor by e. Cis dominant toe. Band R 
represent the factors for black and red-eye respectively. 
Just as we worked out on Mendel’s theory the result to be expected 
from the crossing of yellow-wrinkled and green-round peas, so in this case 
we can work out the result from mating together animals with any two 
of these various constitutions. This has been done for all possible com- 
binations, and the results of the experiments are in good agreement with 
theoretical expectations, as may be seen from a study of Diagram 6, 
which gives the numbers actually obtained from several of these matings, 
as well as those which the theory requires. 
The black-eyed children of the original albino-eyed female mated to 
the hybrid male, all of which carry the factor for albino, or, to put it 
more accurately, lack one colour factor, can be crossed in three different 
ways : 
(1) Pure black x Pure black. 
(2) Pure black x Hybrid black (Black carrying red). 
(3) Hybrid black x Hybrid black. 
Lf we work out the theory for these crosses, just as we worked it out for 
the peas, we find that altogether amongst the offspring, that is amongst 
the grandchildren of the original parents, there will be animals of nine 
different constitutions of eye-colour (compare Diagram 8), namely :— 
4 kinds of black-eyed animals . Pure black. 
Black carrying albino. 
Black carrying red. 
Black carrying both red and albino. 
2 kinds of red-eyed animals. 7 Pure’ red. 
Red carrying albino. 
3 kinds of albino-eyed animals . Albino carrying black. 
Albino carrying red. 
Albino carrying black and red. 
In the actual experiments we have been able to prove that animals of 
all these nine kinds occur, and the numbers also in which they are found 
are in sufficiently good agreement with the theoretical expectation to 
satisfy us of the correctness of the theory. 
In Diagram 9 the actual results of a number of matings in which 
the albinos take part are shown, as these results are specially 
interesting. 
