208 Herbert W. Rand 
extension resembled that shown in Fig. 8, usually a more or less 
definite nipple was present. Fig. 9 shows the appearance of a 
piece of tentacle ligated onto the hydrostatic tube and slightly 
distended under gentle pressure. A nipple, although a short one, 
is distinctly present. This condition appeared thirteen minutes 
after the distal portion of the tentacle had been cut away. In this 
experiment the behavior of the ligated proximal piece of tentacle, 
as well as that of the distal piece which had been cut away from 
it, was watched closely and constantly for forty-five minutes, 
Within three minutes after the cutting away of the distal piece 
the hole in the distal end of the ligated piece had contracted notice- 
ably in area and its edges, at first somewhat angular, had become 
smoothly circular. As the piece alternately shortened and elon- 
gated the size of the hole varied considerably, usually being larger 
when the tentacle was shortened. Its average size diminished 
steadily but very slowly. One hour after the beginning of the 
experiment the tentacle appeared as in Fig. 10. (The figure shows 
an oblique end view of the fragment.) In this slightly elongated 
condition of the tentacle the opening was a small circular pore. 
A whitish zone around the pore indicated a state of contraction 
in the tissues of that region. Four and a half hours after then 
beginning of the experiment the pore was still smaller, being quite, 
invisible at times. In this experiment, and commonly in the others 
the ligated piece usually extended in length only, remaining very 
small in diameter as if under persistent contraction of circular 
fibers. However, during the fifth hour of the experiment the 
tentacle was twice seen to swell out, apparently by a relaxation of 
circular fibers, but in so doing the contraction at the distal tip 
persisted and the pore became no larger. It should be borne in 
mind that in all of these experiments with the pressure tube a little 
internal pressure was applied whenever a tendency to extend was 
noted, for by that means a much clearer demonstration of the con- 
dition of contraction at the distal end was obtained. 
If fragments of tentacles were allowed merely to lie upon the 
floor of the aquarium for twenty-four hours after excision the distal 
cut ends at the expiration of that time were smoothly tapering 
in form, nearly or quite closed, and in the habitually much con- 
