26 INHERITANCE IN SILKWORMS, I 



In the above series there is a striking combination of alternative 

 inheritance in Mendelian manner with marked individual idiosyn- 

 crasies. At first glance these idiosyncrasies seem to depend on sex- 

 dominancy but an inspection of the F 2 generations will show that sex 

 is not the determinant of dominancy. 



Data of a series of crossings between Italian Salmon, *zebra larva, 

 pinkish yellow (salmon) cocoon race and Bagdad, white larva, white 

 cocoon race. 



F t J* Ital. Sal. X J Bagdad; producing all zebra larva, and cocoons 

 varying from dirty white through salmon, pale straw yellow to golden 

 yellow. 



FI <? Bagdad X $ Ital. Sal; producing 133 zebra, and 129 white 

 larvae; all salmon cocoons. 



F 2 <$ Hyb. zebra larva, salmon cocoon, X ? hyb. white larva, 

 salmon cocoon; producing 35 zebra larvae spinning 17 

 salmon to yellow and 3 white cocoons, and 26 white larvae, 

 spinning 1 1 pale salmon to yellow and 4 white cocoons. 

 F 2 $ Hyb. white larva, salmon cocoon, X 5 zebra larva, salmon 

 cocoon; produced 30 zebra larvae spinning all salmon to 

 yellow cocoons, and 33 white larvae spinning 18 salmon to 

 yellow cocoons. 



F 2 <J Hyb. white larva, salmon cocoon, X ? hyb. zebra larva, 

 salmon cocoon; produced 48 zebra larvae spinning 13 salmon 

 to yellow and 9 white cocoons, and 36 white larvae spinning 

 17 pale salmon to yellow and 6 white cocoons. 

 F 2 Hyb. white larva, salmon cocoon, X hyb. white larva, salmon 

 cocoon; produced all white larvae, spinning 25 salmon to 

 yellow and 7 white cocoons. 



F x $ Ital. Sal. X ? Bagdad ; produced all zebra larvae and all white 

 cocoons. 



F 2 Hyb. zebra larva, white cocoon, X hyb. zebra larva, white 

 cocoon; produced 46 zebra larvae spinning 27 white and 

 pale salmon cocoons, and 15 white larvae spinning 10 white 

 and 2 pale salmon cocoons. 



F 2 Hyb. zebra larva, white cocoon, X hyb. zebra larva, white 

 cocoon; produced 40 zebra larvae spinning ^2 white and 5 

 salmon cocoons and 7 white larvae spinning 2 white and I 

 salmon cocoons. 



* Italian Salmon race has two discontinuous types of larvae, viz., Zebra and White, but 

 where the race name is used without qualification I refer always to Zebra type. 



