Abstract
By using a colorimetric method developed by LOWRY et al. (1951), sericin content in cocoon filament was determined and a selection experiment has been carried out toward both direction of high and low values. Moths from cocoons showing either high or low absorbance at 500 mμ (A500) were bred for further selection in successive 5 generations. In G5 the A500 values were significantly different between the high and low lines. Scouring off ratio in the cocoon filament responded in the same way. In the low line both the weight of the cocoon and of the cocoon shell decreased as selection proceeded.
