| Abstract: | In the area between the equatorial and the upper vegetal regions of the egg of the newt, Cynops (Triturus) phrrhogaster, strips of cellophane, ordinary filter paper or Millipore filter respectively were inserted transversely at short distances ahead of the advancing cleavage furrow. When a cellophane strip is inserted across the future path of the furrow at 0.5–0.7 mm beyond the furrow tip, the furrow stops on reaching the position of the inserted cellophane strip. If, however, a strip of the Millipore filter is inserted at the same distances ahead of the cleavage furrow, the furrow reaches the one side of the Millipore filter strip and soon appears on the opposite side of it, just as the furrow jumps across the strip, to continue the previous course. Similar tendency is observed in the experiments on insertion of strips of the ordinary filter paper. It is suggested that certain propagating factors which are necessary to induce formation of the cleavage furrow can go through the pores of the Millipore filter to precede the advancing tip of the cleavage furrow. |
