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 Linncean 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. As 

 already pointed out this is due, on the mutation theory, to the 



