APS 29 1924 
GENETIC STUDIES ON THE SILKWORM 
BY 
Yoshimaro Tanaka 
With PI. I- VI 
I. INTRODUCTORY. 
All works in genetics done during the past fifteen years have increased 
the interest attaching to the silkworm moth, Bombyx viori L., which would 
appear to represent one of the series of animals occupying a truly central 
position among the forms drawing attention from both theoretical and economic 
points of view. In particular, the silkworm affords the material, perhaps, 
most appropriate for the genetic study, not only because there are a con- 
siderable number of races which freely mate together, but because the moth 
is polygamous and the feeding period lasts only 25-35 days. ^ 
In spite of their effort previous observers have directed little attention 
to the genetic interrelations of unit characters or factors. The present ex- 
periments were undertaken in 1910 and are still in progress. The results, so 
far as obtained, were preliminarily published at occasions. In the following 
pages I will give a full account of my experiments down to the year 1915, 
including the formerly reported facts which will be found especially in 
Chapter iv. 
It is, perhaps, worth while to note that the present experiments concern 
in the main not the adult characters, but the larval which are, therefore, to 
1) Besides these, we can see more than two generations a year in bivoltine and polyvoltine 
races; even in univoltines, the eggs may be forced to hatch repeatedly in the same year through the 
artificial methods first discovered by Versom (with electricity) and Duclaux and Bolle (with 
acids'), which have recently been improved by Japanese sericulturists. 
[Jour, of the College of Agr., Tohoku Imp. Univ., Sapporo, Vol. VII, Pt. 3, June, 1916] 
