Wound Reparation—A ctinian Tentacles 199 
its former irregular outline had been smoothed down to an approx- 
imately circular one. ‘Then the stump began very gradually to 
extend, the continued diminishing of the opening being more 
marked as the tentacle expanded. Very soon after the tentacle 
began to extend, the nipple-like condition at the cut end became 
evident. It appeared as if a ring of material around the opening 
contracted more and more sharply, while all the rest of the ten- 
tacle wall was relaxed and distended. After the nipple had be- 
come well formed, the tentacle rapidly expanded and at the end 
of ten minutes the stump had regained practically its original 
dimensions, presenting then the appearance already described 
and represented in Fig. 2. 
In many cases where only a short piece was cut from the tip, the 
injured tentacle was thrust into the mouth and retained there for 
a quarter of an hour or more. In one series of eleven experiments, 
this behavior was observed in six cases. The act of inserting the 
tentacle into the mouth was performed as the tentacle extended, 
after the usual contraction which followed the cutting. During 
the process of extension the tentacle, already closed and bearing 
a nipple, was bent in toward the mouth opening and _ slowly 
pushed into it, while its entrance was assisted by characteristic 
swallowing motions of the gullet. In this way one-half or more 
of the length of the tentacle was engulfed. The walls of the ten- 
tacle were pressed tightly together by the lips of the gullet while 
the unswallowed part of the tentacle remained fully expanded 
and much distended by internal pressure. If I gently pulled the 
tentacle out of the mouth, it was usually reinserted. One cut 
tentacle which had been repeatedly withdrawn from the mouth 
was found reinserted nearly an hour after the cutting. In one 
case the stump of a tentacle whose distal half had been cut away 
was put into the mouth, but I did not observe this behavior in 
any instance where more than half the tentacle had been removed. 
This act took place with such promptness and precision, when it 
took place at all, that I cannot regard it as due to any accidental 
contact of tentacle and mouth. 
The closing of the cut end of a tentacle having been accom- 
plished, the stump thereafter behaved as nearly as possible like 
