Abstract
The contraction ratio (CR) of cocoons was genetically different among silkworm strains. Selection for the CR was carried out successively for three generations by the inbreeding of moths producing cocoons giving high, medium and low CR value. The rernarkable difference was observed in the selection effectiveness upon the CR among these three lines. Reelability of cocoons was also differed among three lines ; the line selected towards the low-CR showed the highest reelability.
