Abstract
”.inode” larval pattern with black colour is a simple dominant character for normal-marking in silk worm, and the symbol U is given to this pattern by Hashimoto (1941). In this experiment “Hinode” pattern was crossed with plain (p). F1 had “Hinode” pattern, and when backcrossed with plain, gave “Hinode” pattern, normal-marking, grey side pattern and plain in the ratio of 1:1:1:1.
The new character, grey side pattern, is developed in the skin of larva with grey colour, longitudinally from mesothorax to the 6th-8th abdominal segments, between the subdorsal and supraspiracular line from the 3rd to the 5th larval stages, and diluted from the 5th stage. Similar digenic segregation is also found in the hybrids between segregates with grey side pattern and normal-marking in that backcross. “Hinode” pattern is, therefore, formed with the interaction of both dominant genes U and P, whereas grey side pattern is brought about by the gene U only.
