Wound Reparation—A ctinian T entacles Bie 
The insertion of an injured tentacle into the gullet seems to me of 
doubtful significance. It might be regarded as a means of closing 
the cut end of the tentacle, but as such the act would appear to be 
a superfluous one, since the cut end 1s already effectively closed 
by the nipple. In structures so small of cross section as the tubu- 
larian stem and the trunk of Hydra the consequences of exposing 
the gastro-vascular cavity cannot be so serious as in the incom- 
parably larger actinian. There is no evidence that internal 
pressure plays the important role in Hydra that it does in the large 
actinian. Further, in these smaller structures the permanent 
repair by the rearrangement process is completed within a com- . 
paratively short time. Accordingly there would seem to be no 
need of such a provisional control of the wound as we have seen 
to be operative in the large actinians. In Tubularia, at least, 
a muscular apparatus capable of such control is lacking. 
The experiments which I have described have shown that the 
behavior at a distal cut end of a detached tentacle is the same, 
so far as the essential features are concerned, as when the tentacle 
is normally attached to the column. The detached tentacle in 
response to a distal cut exhibits the immediate reaction of muscular 
control of the distal cut end as well as the slower structural read- 
justment by means of which the permanent and non-muscular 
closure is effected. There are, as we have seen, two respects in 
which the tentacle is affected by detachment from the column. 
In the first place there is some physiological difference between 
the tissues of a normal tentacle and those of a detached tentacle, 
as shown by the persistent contraction of the detached tentacle. 
Whether this physiological change is caused by the stimulus of 
cutting or by the presence of a cut surface or whether it is possibly 
due to the absence of some inhibitory effect normally exerted 
upon the tentacle by the column, I am not able to say. In the 
second place there is a purely mechanical difference between 
detached and normal tentacles in that the former lack the normal 
internal fluid pressure. These two differences are accountable 
for certain differences in the details of the behavior of attached 
and detached tentacles. Otherwise reparation takes place in 
detached tentacles precisely as it does in attached tentacles. 
