FORM-REGULATION IN CERIANTHUS. 133 



(W) Oral end not expanded; marginal tentacles 0.5 mm., no 

 labial tentacles. 



(V) No tentacles visible. 



In all experimental pieces the diameter of the disc, where such 

 is distinguishable, is, and has been throughout, le*ss than the 

 diameter of the body (Fig. 4), resembling in this respect the 

 earliest stages of typical regeneration. 



Controls. In four pieces marginal tentacles 6 8 mm. (Fig. 5), 

 in fifth about 5 mm.; all with labial tentacles about 0.5 mm. 



In all of the controls the diameter of the disk is greater than 

 that of the body, the whole being somewhat trumpet-shaped like 

 the normal animal. 



From this time on the experimental pieces were left undisturbed 

 in order to determine whether they still had the power to close 

 and complete the retarded regeneration. The controls were 

 discarded. 



December 28. --(a) Aboral end closed by new tissue ; body 

 distended with water ; marginal tentacles 5-6 mm., slightly more 

 blunt than normal tentacles but much less blunt than at previous 

 examination ; labial tentacles 0.5 mm. . 



(b] Aboral end closed by new tissue ; body distended ; mar- 

 ginal tentacles 7-8 mm., still somewhat more blunt than normal ; 

 labial tentacles I mm. 



(c] Aboral end closed by new tissue ; body distended ; mar- 

 ginal tentacles 6-7 mm., slightly more blunt than normal ; labial 

 tentacles 0.5 mm. 



In all three pieces (Fig. 6) the diameter of the disc is still 

 somewhat less than that of the body, but is relatively greater 

 than on December 17, /. e., the oral end is expanding. The 

 aboral ends bear slight knobs and irregular masses of old tissue, 

 which represent small shreds and strips of the old body-wall 

 which had rolled into rounded masses during the experiment and 

 are now undergoing absorption. 



(</) New tissue at aboral end does not close end completely 

 as yet ; body is only slightly distended ; marginal tentacles 1 1.5 

 mm., blunt ; labial tentacles minute buds. 



(r) Widely open aborally, about as before in appearance. 



January 11, 1903. (a) Body distended in normal manner 



