FED 27 1909 
A Sport of the Silk-Worm, Bombyx Mori L., 
and its Hereditary Behavior. 
By K. Toyama. 
(Zoological Institute, College of Agriculture, Tokyo Imperial University.) 
Amongst our experienced silk-worm breeders it is known that 
certain breeds occasionally throw off some red worms, but as to how 
‚they are produced and how they behaved in inheritance much obscurity 
still prevails. 
In the year 1905 I found some red worms suddenly arisen from 
a cross between two normal black breeds, and thus a series of 
experiments was conducted with the intention of working out the 
laws of its inheritance. The results will be given in the following pages. 
The first generation (F,). 
In the spring of 1905 we crossed a Japanese univoltine breed 
called “Datenishiki’ with the male of a tetravoltine breed ‘“‘Tobuhime’’, 
and obtained 18 batches of eggs. 
The newly hatched worms of both parent breeds are brownish 
black, i. e., normal in color. In the fifth stage, however, we have 
only commonly marked worms in the former breed and both common 
and pale worms in the latter. 
The eggs obtained from this cross hatched out on the 20oth—2ıst 
April of the next year. All the worms when hatched were brownish 
black in color, that is to say, they remained true to the parents. 
The second generation (Fy). 
The dark worms derived from the cross above mentioned spunn 
cocoons on the 23rd—26th May and the moths emerged on the 
8th—ıoth, June, 1906. 
From these moths we obtained 627 batches of eggs which hatched 
on the 21st—z22nd June of the same year. The newly hatched worms 
Induktive Abstammungs- und Vererbungslehre. I, 12 
LIBRARY 
NEW YORK 
BOTANICAL 
GARDEN. 
