198 Herbert W. Rand 
millimeters long was clipped from the end of each of four of the 
smallest tentacles of a small individual of Condylactis. “The four 
tentacles contracted down close to the disc, but there was no 
marked contraction of the disc itself, or of other tentacles. In less 
than one minute after the cutting the cut ends were closed, the 
characteristic nipples had appeared, and all four tentacles were in 
process of extension. Pieces of similar size were then clipped 
from the tips of four of the largest and most fully extended ten- 
tacles of the same animal. ‘These larger tentacles contracted to 
about one-half their former length—no more. ‘The closing of 
the cut ends and formation of nipples were accomplished within 
four or five seconds and the tentacles were again fully extended 
within one minute. Under these circumstances one has free 
opportunity to see all that can be seen of the process of closing. 
Only a brief instant elapses before the cut edges begin to curve 
inward so as to diminish the size of the opening. ‘Then, as the 
tentacle begins to extend, the nipple is formed by a gradual tight- 
ening of the wall around the opening. ‘This experiment was 
repeated upon eleven tentacles of other individuals. In all cases 
the tentacle shortened almost to the disc. This contraction is not 
instantaneous, but occupies one or two seconds of time. In four 
cases the nipple was formed during the contraction and the ten- 
tacle then immediately began to extend with the end already 
closed by a strongly developed nipple. A distinct nipple was 
formed in every one of these eleven cases. 
In one experiment, where the distal third of a tentacle was cut 
away, the contraction of neighboring parts was so much less than 
usual that the cut tentacle remained in view, so that I was able to 
watch the closing process from the beginning. After the cutting 
the tentacle instantly collapsed, and more slowly contracted close 
to the disc. Immediately after this contraction the opening at 
the cut end of the stump was quite irregular in outline—not cir- 
cular—and in area not noticeably larger or smaller than it was at 
the instant before contraction took place, but its edges were every- 
where slightly bent inward. Within the second minute after the 
operation the area of the opening began to diminish rapidly. 
At the end of three minutes the opening was markedly smaller and 
