lino 



Toyama, On certain characteristics of the Silk-worm etc. 



(3.) 



W(41) 

 (1 W 



F, 



Expectation 



F., W (216) + Y (108) W (283) + Y (315) W (05) + Y 255) 



Kxpectatiou (3 W -f- 1 Y) (I W + 1 Y) (1 w + 3 y). 



F 



2 



Expectation 



4. 



(F, W X F, Y) 



W(66)"+ Y(41) 

 (1 w + 1 y). 



W = White, Y = Yellow. 



As we expected, both Coutagne's and Kellogg's results gave 

 three sorts of F i broods: namely, all White, all Yellow, and a 

 mixture of both white and yellow in an approximate proportion of 

 1 W : 1 Y. In the white F i series, the white behaved as dominant 

 and in the yellow series the white is recessive towards yellows, 

 their proportion being approximate to the expected number, while 

 F t white mated with F 1 yellow gave a mixed F 2 . In the third 

 series of Coutagne's summary, there are found six white cocoons 

 in F 2 yellow matings which are not demanded by the theory, and 

 in certain of Kellogg's matings the proportion of white and yellow 

 does not accord well with the ratio which our hypothesis demands. 

 The former was possibly due to some accident, and the latter to 

 the small number of worms reared in each mating. 



Certain egg-characteristics. 



Lastly, we shall notice the phenomena of inheritance observed 

 in certain egg-characteristics in which the results seemed to us to 

 be more irregular than in the case of varying dominance of cocoon- 

 colour quoted above. 



The ordinary colour of Japanese silk-worm eggs is a light 

 greenish -white when newly laid. With the formation of the 

 blastoderm, it gradually becomes of a brownish tint which at last 

 turns into brownish-slate shaded with some light pink or purple. 

 This is the normal colour of the egg of the Japanese breeds used 

 in our experiments. 



Among these normal eggs, we find sometimes many variants 

 which are decidedly different from the normal ones, for instance, 

 light brown, bluish-grey, orange, light orange, greenish white, 

 crimson-red, and many others. 



As to the shape the normal one is oval, slightly pointed at 

 one end where a micropyle is situated. It is slightly flattened 



