Wound Reparation—A ctinian Tentacles 195 
tentacles at base, 10 or 11 mm.; diameter near tip, nearly 4 mm. 
The following experiment was repeated some twenty-five times | 
with uniform results. 
When the actinian was well expanded, a pair of sharp scissors 
was cautiously brought near a tentacle without contact with any 
other tentacle, and by a single quick clip the tentacle was severed 
about midway of its length. ‘The behavior of the excised frag- 
ment will be considered later. Immediately after the cutting, 
the stump of the tentacle collapsed and contracted down close to 
the disc. Not quite simultaneously with this contraction of the 
injured tentacle, but closely following it, several of the tentacles 
nearest the cut one contracted more or less and in such a way as 
to bend in over the cut tentacle, while at the same time the region 
of column and disc bearing the contracted tentacles became 
deeply invaginated. This invagination took place so that the 
cut tentacle was at its deepest part. As a result of all this contrac- 
tion, the injured tentacle was completely engulfed by surrounding 
parts, for the neighboring tentacles curved in over the invaginated 
region so that the cut one was deeply hidden from view. I did 
not attempt to prevent this contraction for, even if it had been 
possible to prevent it, I preferred not to introduce into the con- 
ditions affecting the animal any disturbing influences beyond the 
operation itself. After a period of time which varied greatly in 
different experiments, usually amounting to five or ten minutes 
when the cut was made about midway of the length of the ten- 
tacle, the contracted region of the animal began to relax and ex- 
pand. When the expansion had progressed far enough to bring 
the cut tentacle into view, it was almost invariably found to pre- 
sent the conditions represented in Fig. 1 (Plate 1). The stump of 
the injured tentacle was somewhat distended and its cut end 
appeared closed. ‘This closed end was hemispherical except for the 
presence, at its center, of a small cylindrical projection. The 
expansion of the contracted region having once begun, progressed 
rapidly until, usually within fifteen minutes after cutting, all the 
uninjured tentacles were fully extended, while the stump of the 
injured tentacle had extended to nearly its original dimensions. 
Fig. 2 represents the condition of two cut tentacles as they appeared 
