Experimental Hybridizing 97 
The gray (F,) hybrids were paired with albinos and 537 
young produced, of which 261 were albinos and 276 colored — 
a close approximation to the expected equality. The colors 
were of various kinds, but gray greatly predominated. When 
gray (F,) hybrids were inbred, they produced 119 albinos and 
308 colored —a rough approximation to the expectation of 
I to 3. . 
Haacke has published the results of a large number of crosses 
between white mice, colored mice, and Japanese waltzing mice. 
Although his experiments were not carried out to test the Men- 
delian law, yet, as the author points out, they closely conform 
to this law. Haacke states his general conclusion in a some- 
what involved way, namely, that the possible races of species 
equal the number of possible kinds of germ-cells, z.e. equal 
a sum that consists of as many factors as a particular species 
has independently variable qualities or germinal portions. In 
the sum each factor equals the number of all possible modifica- 
tions of its properties. 
LITERATURE, CHAPTER VII 
ALLEN, G.M. The Heredity of Coat Color in Mice. Proc. of the Amer. 
Acad. of Arts and Sci. XL. 1904. 
Bateson, W. The Present State of Knowledge of Color-Heredity in Mice 
and Rats. Proc. Zool. Soc. II. Londen. 1903. 
Castte, W. E., and ALLEN, G. The Heredity of Albinism. Proc. Amer. 
Acad. of Arts and Sci. XXXVIII. 1903. 
Cutnot, L. La loi de Mendel et l’hérédité de la pigmentation chez les 
souris. Arch. Zool. Expér. et Gén. Sér. 3, X. Notes et Revue. 
1902. 
La Toi de Mendel et 1’hérédité de la pigmentation chez les souris. 
Compt. Rend. CXXXIV. Paris. 1902. 
L’hérédité de la pigmentation chez les souris (2™° note). Arch. Zool. 
Expér. et Gén. Sér. 4,1. Notes et Revue. 1903. : 
L’hérédité de la pigmentation chez les souris (3"° note). Arch. Zool. 
Expér. et Gén. Sér. 4, II. Notes et Revue. 1904. 
Les Races Pures et leurs Combinaisons chez les souris. Arch. de 
Zool. Expér. et Gén. Sér. 4, III. Notes et Revue. 1905. 
DarsisHIrE, A. D. Note on the Results of crossing Japanese Waltz- 
ing Mice with European Albino Races. Biometrika, II. 1903. 
Second Report on the Result of crossing Japanese Watzing Mice with 
European Albino Mice. Biometrika, II. 1903. 
H 
