Further studies on regeneration in Asterias vulgaris

Abstract

1. Out of a total of 1914 star-fish examined, 206 or 10.76% were regenerating under natural conditions. One or more arms were growing out from the disc in all cases excepting one in which the distal portion of an arm was being restored. 2. Single arms of Asterias vulgaris live from two to three weeks whether the digestive coeca be removed or not. They are not able to regenerate the rest of the animal. 3. If a piece of the disc containing only the madreporite and the stone canal remains attached to an arm, regeneration of the missing parts occurs in exceptional cases. 4. The disc alone will regenerate all of the missing arms. One-half of the disc does not regenerate owing, doubtless, to the great extent of cut surface. 5. If a vertical cut be made across the disc from the intersection of two arms to the mouth, one or two extra arms grow out from the wound in the disc in a small per cent of the experiments. In a great majority of cases the cut edges come together and unite completely, no extra arms being formed. 6. The madreporite has no fixed position in the new disc. 7. If the arms of Asterias vulgaris are mutilated by cutting wedge-shaped, semi-circular or rectangular pieces from them, the missing parts are regenerated and the normal shape of the arms is completely restored in the course of three months.