Abstract
1) The distribution of germ cells in embryos was observed in four strains of silkworm. It was found that the distribution of germ cells does not confined to any definite bodily segments, but varies according to individuals or strains. Germ cells almost occupy their characteristic position distributing from the 6th to 8th segment, while some are found in the gnathal, thoracal and abdominal segments, besides the above segments.
2) The range of distribution of germ cells in various parts of the embryo seems to be determined at the time of their first appearance, which occurs at the stage of germ-band formation. The distribution of germ cells seems not to undergo influence of expansion or contraction of embryo. The cause which induced the distribution of germ cells in gnathal and thoracal segments is, however, unknown; it seems that it is attributable to the lack of affinity among germ cells.
3) The distribution of germ cells to two sides of the body seems to be taken place by chance. There are some individuals in which the number of germ cells is disimilar in both sides.
4) The germ cells which are found distributed in some segments other than the 6th to 9th segment, take no part in the gonad-formation, and they are destind to degenerate.
