REGENERATION IN THE POLYCHÆTE CLYMENELLA TORQUATA

III. EFFECT OF LEVEL OF CUT ON TYPE OF NEW STRUCTURES IN ANTERIOR REGENERATION

¹ From the College of the City of New York and the Marine Biological Laboratory, Woods Hole

1. Six or fewer anterior segments were exactly replaced.

2. Only 2 worms produced buds at cuts posterior to the eleventh segment. Most pieces cut at such levels died relatively soon.

3. In the region from the seventh to the eleventh segments there was an increase in deaths, a decrease in ability to produce complete buds, and a marked increase in the number of irregular buds.

4. At the ninth to eleventh segments a number of buds were of the usual type but possessed fewer segments than had been removed. Available evidence points to the conclusion that regenerates of this type do not undergo any metamorphosis of segments or any increase in number of segments at the posterior end of the body.

5. In several buds a pair of parapodia appeared on the peristomium which is ordinarily asetigerous.

6. Eleven cases of heteromorphic or double structures appeared, all confined to cuts at segments 10, 11 or 12. Two of these were double parts of the penistomium. Two were heads with extra structures possessing neither head nor tail characters. Two were heteromorphic tails without extra structures. Three were heads, each with a secondary tail outgrowth. Two were tails with extra outgrowths.

7. A most interesting bud appeared on one piece cut at the ninth segment. It possessed the following features: a segment split on the left side, a half-segment intercalated on the right side, and two spiral segments. One of the latter was a left-hand spiral of one and one-half turns, the other a right-hand spiral of possibly a little over one-half turn.

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