194 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
A somewhat similar case is described by Strasburger (: 00), in which a 
smut, Ustilago violacea, when present as a parasite in the female plant of 
Melandryum album, causes the female organ of the latter, the pistil, to 
remain undeveloped, while the anthers, normally mere rudiments, grow 
to a large size and actually form pollen-mother cells, which the fungus 
then attacks and destroys. In this case it is the male character which, 
though normally recessive, is made to appear upon destruction of the 
genital fundament of the opposite sex ; in the case of Carica papaya, it 
is the female character which behaves in a similar way. 
The objection may be offered that certain of the examples cited really 
belong in the category of imperfect hermaphroditism, or at any rate of 
potential hermaphroditism. This I freely grant; I would even go 
farther and say that a// animals and plants are potenteal hermaphrodites, 
for they contain the characters of both sexes, but ordinarily the characters 
of one sex only are developed, those of the other sex being latent or else 
imperfectly developed. 
In true hermaphrodites, however, the characters of both sexes exist 
fully developed side by side, as do the gray and the white coat-colors in 
spotted mice. The true hermaphrodite, then, is a sex-mosaic ; to the 
heredity of sex, in its case, we may expect to find applicable the 
general principles of mosaic inheritance. "_ 
The difference between a hermaphrodite and a dioecious animal is 
precisely parallel to that which exists between a spotted and a normal 
hybrid mouse. In the hermaphrodite, as in the spotted mouse, two 
characters ordinarily alternative exist as co-ordinates, side by side ; in 
dioecious animals, as in ordinary hybrid mice, the same two characters 
exist in their more usual relationship of dominant and recessive. The 
only difference between the two classes of cases is this. In coat-color 
among mice gray is variably dominant over, or balanced with white, 
but never recessive toward it. But in dioecious animals the male char- 
acter is sometimes dominant over the female, sometimes balanced with 
it, and sometimes recessive toward it. This condition, though not paral- 
leled in the illustration chosen (coat-color of mice), is not without a 
parallel among other Mendelian cases. For, Tschermak (: 00) finds that 
in certain crosses among peas, one character may be, with reference to 
another, sometimes dominant, sometimes recessive. 
We have seen that spotted (hybrid) mice commonly produce gametes 
which are, like themselves, mosaic, DA, whereas ordinary (gray) hybrids, 
in which white is recessive, produce “ pure” gametes, either D or A, in 
accordance with the principle of segregation. Similarly the sexv-mosaic, 
