Cats
by T Terada and T Watanabe in a 1930s Japanese journal. This hypothesis is now being
investigated using computer simulation. There are several "unknowns" with the current
hypotheses: the relative frequencies of the 10 grades of white spotting given that white
spotted cats may be either SS or Ss; the relationship, if any, between birth order and
patterning; and whether the "swirled" pattern is related to any birth defects or any difficulties
during pregnancy. The melanocyte migration hypothesis may not contain the whole story,
especially where swirled patterns, black feet on white socks and skunk stripes are concerned.
Some cat breeders believed there were flaws in the conventional melanocyte migration
theory. For example a breeder working with American Shorthairs has been crossing Van
pattern American Shorthairs to bicolour and spotted Van pattern cats since the mid 1990s. She
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