240 Toyama and Mori. 
colour factor by Y and y respectively, then the zygotic compositions 
of various white and yellow forms will be as follows: 
a) SSYY — homozygous dominant white, with homozygous colour 
factor. 
b) SSyy = homozygous dominant white, without colour factor. 
c) ssyy — homozygous recessive white, destitute of both the 
suppressing and the colour factors. 
d) SSYy = homozygous dominant white, with heterozygous colour 
factor. 
e) Ssyy = heterozygous dominant white, without colour factor. 
f) ssYY — homozygous yellow. 
4. At present, we are unable to distinguish these various whites 
from one another by their outward appearance. Consequently, random 
matings may take place between these various whites and the yellow, 
and produce rather complicated results. Thus the phenomena of 
inheritance of white characteristic are sometimes apparently incon- 
sistent with Mendelian principles. So-called varying dominance of 
white cocoon colour of certain breeds and inconsistent proportions 
of whites and yellows found in certain crosses, may arise from such 
random crossings. 
5. As far as we are aware, Japanese, Chinese, or Siamese whites 
studied by KeELLocG (9), IsHIWATA (6), QuAJAT (12) and ToyAMA 
(13a, c) are all recessive ssyy, those reared in Europe, such as Italian 
white, Sina blanc, Blanc des Alpes, Bagdad white (TovamA (I3b), 
COUTAGNE (3), KELLOGG (9), QUAJAT (I2)) are SSYY, SSYy, Ssyy or a 
mixture of various dominant and recessive whites. 
Zoological Institute, College of Agriculture. 
Tokyo Imperial University. 
Works referred to. 
. Batgson, W. Mendel’s principles of heredity. Cambridge 1909. 
. CastLE, W. E. Double matings of silkworm moths. 1911. 
WwW NH 
. CouTAGNE, G. Recherches expérimentales sur l’Hérédité chez les vers a soie. 
Bulletin scientifique de la France et de la Belgique 37 1902. 
4. East, E. M. Inheritance in maize. Bull. 167. Conn. Agric. Exp. Station. 1911. 
5. GREGORY, R. P. Experiments with Primula sinensis. Jour. of Genetics 1 1911. 
6. IsHrwata, S. In inheritance of the silk-worm. (Japanese.) 1908. 
7. KEEBLE, Petrrew and Jones. The inheritance of peloria and flower colour in 
foxgrove (Digitalis purpurea). New phytol. 9 1910. 
8. KEEBLE and PELLEW. White-flowered variety of Primula sinensis. Jour. of 
Genetics 1 1911. 
