Till lately we spoke of the relations between the gray color of the mouse to the black color in terms of dominance. Those terms, strictly speaking, should only be applied to members of the same allelomorphic pair. We can perhaps best express the relation between the gray and the black by the use of the metaphor ‘higher and lower’, and I therefore suggest the term epistatic as applicable to characters which have to be, as it were, lifted off in order to permit the lower or hypostatic character to appear.