THE FATES OF SEGMENTS FROM TUBULARIA PRIMORDIA

Abstract

Reconstituting primordia of Tubularia crocea from Woods Hole, Mass., were mutilated at various stages of development, to give segments taken from different parts of the primordia according to the distribution of regenerative pigment. When such segments were allowed to develop in isolation, it was found that as regeneration proceeds the ability to form proximal tentacles is progressively lost to the primordium as a wave which moves proximally, beginning only 2 hours after the original decapitation, and long before visible pigment is present. By the time the single pigment band stage is reached, the pigmented area appears unable to support proximal tentacle formation when isolated, even though at the later 2 band stage the proximal band does produce proximal tentacles. Ability to form distal tentacles is never lost to any segment that is capable of reconstituting at all. However, proximal segments from advanced primordia develop a tendency not to form distal tentacles in time to keep up with proximal tentacle formation. It is concluded that the pigment of Tubularia plays no causal role in reconstitution, but is a by-product of the activity that accompanies the reconsti-tutive process.