No. 569] 



REGENERATION 



mentioned. However, sometimes evisceration is incom- 

 plete, as the following examples will show. On the morn- 

 ing of August 4, a Thyone, which we shall later speak of 

 as individual H, was found eviscerating in an over- 

 crowded aquarium jar. While the process usually re- 

 quires only a few seconds, or at most a few minutes, 

 the intestine in this case was not completely thrown out 

 until two or three hours later. This animal lived until 

 killed at the end of twenty-one days. In the afternoon 

 of the same day on which individual H eviscerated, an- 

 other Thyone was found with the process only partially 

 complete. Five hours later the intestine was still re- 

 tained, and scissors were used to cut it off at its anterior 

 end near the stomach. Though this Thyone received 

 equally good care it died at the end of two days without 

 further evisceration. A third specimen was found in- 

 completely eviscerated on the above date, but it was 

 allowed to stand until the next morning ; at this time the 

 injured end was open, the intestine was still within the 

 body cavity and a part of one of the branchial trees was 

 protruding. The intestine was pulled out and broken 

 off, after which the branchial tree was retracted and the 

 injured end partially closed. This animal also died at 

 the end of two days. A fourth Thyone was seized and 

 by squeezing was forcibly caused to throw off the usual 

 parts except the following : a part of the stomach, most 

 of the intestines, and some of the retractor muscles 

 which had broken off near their esophageal end. The 

 next morning it had expelled the remainder of the 

 stomach and intestine, two complete retractor muscles, 

 and some debris which had escaped from the intestine 

 into the body cavity. The anterior end of the part re- 

 maining appeared ragged and imperfectly closed. It 

 died on the third day. It is probable that the two re- 

 tractor muscles last expelled were broken off at their 

 posterior ends by local constriction, not when the body 

 was under pressure. A fifth animal, which we shall 

 designate as individual M, was found partly eviscerated 



