136 C. M. CHILD. 



vent union of the cut surfaces and thus the closure of the piece. 

 Such pieces live for months in many cases, undergoing gradual 

 closure from some region where approximation of cut surfaces 

 renders possible the formation of new tissue between them. 

 Sometimes the end or ends close readily but closure along the 

 side is delayed and in cases of spiral inrolling closure of the end 

 is possible only on the innermost part of the spiral and closure 

 of the sides, not at all. These pieces present an almost infinite 

 variety, but in all their forms afford important evidence as to 

 some of the formative factors in Cerianthns. Without recogni- 

 tion of the method of growth of new tissue between cut surfaces, 

 and the relation between tension due to internal water-pressure 

 or other causes and growth of new tissue almost every one of 

 these pieces might be described in detail for scarcely any two are 

 alike --as an "abnormality." If, however, we attempt to study 

 the special conditions and the reactions to them in each case we 

 find that the differences and "abnormalities" are not difficult to 

 interpret. A number of pieces in which closure was prevented 

 or delayed by the manner of inrolling are described below. 

 These are selected from a much larger number which show 

 various differences in detail from those described. I have en- 

 deavored, however, to select pieces which should show as far as 

 possible the principal "abnormalities." The account will serve 

 both as evidence upon the question of water-pressure and regen- 

 eration and as a description of the course of regeneration in 

 the respective pieces. In most cases these experiments were 

 performed without controls, so that it is impossible to determine 

 exactly how much the first appearance of the tentacles is delayed ; 

 it will be sufficiently evident, however, that it is delayed. In the 

 figures illustrating the inrolling of these pieces the lines employed 

 for shading were so drawn that they also indicate in a general 

 way the longitudinal striping of the body and thus show the 

 direction in which the various parts are rolled inward. 



Series 1 1. 



September 12, 1902.- -Three specimens were cut transversely 

 a short distance aboral to the oesophagus (Fig. 7) and then split 

 longitudinally on one side (Fig. 8). After section they were 

 allowed to remain undisturbed. 



