1.
The experiments show that
  • When a hydranth is picked off the stolon another normally regenerates from the same spot.

  • When the nodal coenosarc is exposed to sea water the probability of hydranth regeneration is much reduced and stolons may grow.

  • A similar exposure of the coenosarc in the middle of an internode results in branch stolon growth at about the same frequency as at a node but hydranths do not grow.

  • Cutting the coenosarc does not affect the structure which grows, but where the stolon is cut at a node and a hydranth regenerates it does so at a distance of 0·3–0·6 mm from the node.

  • Grafting a hydranth into the side of the stolon at a node usually prevents hydranth regeneration but the inhibition ceases when the graft is made at distances greater than 0-3 mm from the node.

  • There is some evidence that hydranth regeneration is preceded by the development of a contractile growth region in the stolon.

2.
It is concluded that
  • A node has a latent morphogenetic capacity to enable hydranths to grow there, a capacity not demonstrated in the middle of an internode.

  • Local exposure to sea water reduces the morphogenetic capacity of stolon coenosarc for hydranth growth and increases it for stolon growth.

  • Hydranth growth may require the earlier formation of a contractile growth zone.

  • An existing hydranth usually inhibits the initiation of another hydranth at or close to its junction with the stolon, perhaps by preventing the formation of such a growth zone there.

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