MENDELIAN FACTORS IN THE SILKWORM. 
95 
lire of dominant and recessive whites. In this paper Toyama represents 
the characters in question as follows : 
Dominant white (W), Recessive white <w), 
Yellow ( Y), 
and assumes that an allelomorphic relation exists not only between W and 
W, but also between Y and W or w. Adequacy of this assumption, how- 
ever, may perhaps be doubted from the standpoint of the presence and 
absence hypothesis. 
The following discussion on the Mendelian genes in the silkworm is 
based upon my experimental results as well as those obtained by previous 
observers. As my experiments, however have been concerned chiefly with 
the inheritance of larval markings and cocoon colours, a stress in the present 
paper is naturally laid on these characteristics. 
The Author’s Factors . 0 
I) Factors For Larval Markings. 
1) N. Common or normal pattern. 
The full-grown larva which contain this factor is provided with three 
pairs of distinct markings, its ground coat-colour being white or faintly 
shaded. The first pair of the markings, “ocular’' pattern or “eye-spot” as it 
is often called, occurs on the second segment, the second pair, “horse-shoe” 
or anterior “lunule”, on the fifth segment. The last pair which is found 
on the eighth segment is smaller and less conspicuous than the preceding 
two. The noimal pattern is most common in the Japanese races, hence the 
name, but it is also found in other Asiatic and European races. 
The common pattern is epistatic to the plain, but' hypostatic to the striped, 
zebra and moricaud. (Experiments: Toyama, Kellogg, The Author.) 
1) Probably there may be a considerable number of genetic factors in regard to the 
inheritance of larval markings and cocoon-colours, but I take into consideration only 
those characters which hereditary behaviours are exactly known. The inter-relations of 
these factors have been confirmed, as is stated elsewhere, by numerous experimental data 
furnished by various observers including those of the author himself. 
