A Study on the Mechanism of Cleavage in the Amphibian Egg*

Abstract

1. In the eggs of the salamander, Triturus pyrrhogaster, there is an area extending about 1 mm. ahead of the advancing tip of the cleavage furrow where preparation for furrow formation is going on. 2. Severance of this area ahead of an advancing furrow tip does not stop the progress of the furrow. The furrow continues from this area. 3. The cleavage furrow of Triturus pyrrhogaster eggs advances strictly along a straight line. 4. A cut made across its path ahead of a furrow is healed as the furrow tip approaches sufficiently to allow its straight passage. 5. An excised piece of cortex which includes material taken from within 1 mm. of an advancing furrow tip will form a furrow and divide.