The aulthor compared several quantitative chairacters of the silkworhl between parrents and F1 hybrids which were reared in Autumn, in order to analyse a real effect of heterosis. The following signs are used to simplyfy the mention, for the work; D is representing the, <lifference of quantitative values of the parents, M the mean value of the parents, so called mid parents value, and 8 the effect of heterosis e, i, F1 -M . Heterosis of several characters is similariy with each other, so at present the author describes some typical characters for example the percentage of hatching eggs total cdcoon weight, Iength of fibre and size of fibre. In general, the results, of comparison are as follows:
