A. Regeneration of the anterior and posterior halves of the isolated segment. At left is a diagram of the isolated segment showing the transection plane. In the center, the anterior (h) regeneration of the anterior half and the anterior (h) and posterior (t) regeneration of the posterior half are diagrammed. At the right are photographs of living regenerates corresponding to the diagrams.

B. Posterior regeneration of the anterior portion of segment 13 occurs when it is left attached to the first 12 segments. At left is a diagram of the worm showing the transection plane, which corresponds to that in A. In the center is a diagram of the posterior (t) regeneration. At the right is a photograph of a corresponding living regenerate.