Other Kinds of Hybridizing 157 
characters of the ass are more prepotent. The lion has been 
crossed with the tiger and an intermediate hybrid produced. 
The brown bear, crossed with the polar bear, gave a mixing of 
colors with the head and neck white. Darwin states that the 
pheasant crossed with domestic fowls gives a hybrid, showing 
the pheasant characters “‘prepotent.”” Darwin describes a cross 
between the penguin variety of the common duck and the Egyp- 
tian goose that is intermediate in character. 
Mosaic Inheritance 
A mosaic character sometimes appears when differently 
colored individuals are mated. Each character appears in its 
pure form over certain regions. Thus when a gray and a white 
rat are crossed, individuals sometimes appear that are mosaics, 
but it is questionable in this case, and perhaps in all such cases, 
whether the results may not be due to a latent mosaic character 
coming to light. As has been pointed out, offspring of the 
same litter may be different, some being of a single color, others 
mosaic. Whether spotted or piebald, domesticated races — horses, 
cattle, dogs, cats, etc. — owe their origin to a cross between two 
uniformly but differently colored parents, or are themselves 
sports that breed true, or have been back-crossed, is an open 
question. In pigeons, as we have seen, the mosaic character of 
the offspring is apparent. The results are complicated, how- 
ever, by the ancestral (latent) blue color appearing in parts of 
the body. The inheritance of the mosaic pattern in mice and 
guinea pigs has been already discussed. 
Hybridization between Linnean Species 
Most wild species of animals and plants differ from each other 
in more than in a single character. In the great majority of 
cases it is perhaps not going too far to state that species differ 
in all their characters — in some parts more, in others less. Ag 
already pointed out this is due, on the mutation theory, to the 
