MEROGONY AND REGENERATION IN RENILLA. 2IQ 



of these formed no tentacles, peduncle or mesenterial filaments, 

 and only four mesenteries. Both the other two developed six 

 mesenteries and rudimentary tentacles, one pair of short mesen- 

 terial filaments ; only one of them formed a peduncle. This 

 case indicates that the number of mesen cries is not specified at 

 this period ; for although none of the larvae produced the full 

 number the total number formed from the original egg was six- 

 teen. 



(c) EXPERIMENTS ON REGENERATION IN THE YOUNG COLONIES. 



My principal object in studying the young colonies was to 

 examine the relation between morphallaxis and neomorphosis (to 

 adopt Morgan's terms) for which purpose such an organism as 

 Rcnilla offers obvious advantages, and also to ascertain, if possible, 

 how far the process of bud-formation is capable of regulation. 

 The main results reached by Torrey were : (i) That the polarity 

 of the primary polyps was never reserved, a polyp always regener- 

 ating at the anterior end of a piece and a peduncle at the posterior 

 end ; (2) that the power of regeneration was confined to the 

 budding zone ; (3) that after oblique section, a remoulding of 

 the old parts occurred by a regulation "in a plastic fashion," 

 but he did not succeed in following the later changes long 

 enough to ascertain whether this plastic remoulding was perma- 

 nent, and involved the establishment of a new axis of symmetry. 

 Like Torrey, I found that when the peduncle was removed, at 

 any level, a new peduncle very quickly reappeared ; that removal 

 of the axial polyp by transverse section led to regeneration of 

 that polyp ; and that as a rule a severed peduncle did not regener- 

 ate a new axial polyp at the anterior end ; and that by oblique sec- 

 tion through the budding zone two colonies might be produced 

 from one. On some points, however, my results differ from his, 

 while they give a pretty definite answer to the undecided ques- 

 tion regarding the phenomena of remoulding. 



i. In a single case a reversal of polarity was obtained from 

 a colony having five buds that was cut into three pieces by sec- 

 tions anterior and posterior to the budding zone as shown in Fig. 

 2, A. As a rule after operations of this type, only the middle 

 piece, containing the budding zone, regenerates a perfect colony, 



