WOUND CLOSURE AND POLARITY IN METRIDIUM 467 



tentacle fragment always collapsed and the edges of the tentacle 

 stump rolled in slightly. If the edges were successfully brought 

 together, the bristle was then left in the lumina of the tentacle 

 stump and the fragment, and the fragment was held in place for 

 a time by forceps. To graft to a stump such a tentacle fragment 

 in its normal orientation was less difficult than in the reversed 

 orientation, because the fragment, as when free, tended to move 

 in the direction of its original basal end. As this tendency in the 

 reverse graft was away from the stump, the fragment had to be 

 held to the stump against the action of its cilia. 



The graft of a fragment on to an attached stump in normal 

 orientation was made twice successfully. On the following day, 

 the grafted tentacle fragment responded to touch like an excised 

 tentacle, while the stump to which it was grafted was not included 

 in this response unless the stimulus was severe. Twenty-four 

 hours after grafting in one case, forty-eight in the other, the tip 

 of the grafted piece was cut off. Thereupon the cut end closed 

 with the formation of a nipple, as in a normally attached tentacle. 



The reverse graft was successfully made only once, and this 

 was not very satisfactory. Whether the proximal end of the 

 fragment, which was reversed in the process of grafting so that it 

 became the distal end of the tejitacle, remained open when the 

 animal was returned to normal sea water, could not be determined, 

 since the animal remained contracted for some time after the 

 operation. When the grafted tentacle could be seen, the end was 

 found to be open; but after three days the graft was constricted 

 off and was dead. 



Two tentacle fragments cut at both ends were held together on 

 a bristle, or were held in contact between pieces of cover glass. 

 By these means, a number of reverse grafts with the bases together 

 and a few with the tips together were made. Grafts of the former 

 kind were sometimes found among the fragments in the chlore- 

 tone solution when two fragments, moving as they do in the direc- 

 tion of their bases, had opposed each other long enough for the 

 edges to unite. The grafts were kept in chloretone for eight to 

 ten hours, and thereafter in sea-water. The line of union of the 

 two fragments was marked by a groove. This groove remained 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 13, NO. 3 



