Stiulirs on Regulation 371 



ing special consideration. As will appear, however, they afford 

 strong support to the hypothesis which has served for interpreta- 

 tion of the other phenomena: indeed a consistent interpretation 

 seems scarcely possible on any other basis than that of functional 

 regulation. 



I Intestinal Regulation in Correlation with Posterior Form- 

 Regulation 



a In the Prepharyngeal Region 



The process of form-regulation m prepharyngeal pieces contain- 

 ing the cephalic ganglia consists essentially (Child '05a) in the 

 redifFerentiation of the posterior part into a new postpharyngeal 

 region and the formation of a new pharynx between this and the 

 new prepharyngeal region. Regeneration is limited to the extreme 

 posterior end of the piece and amounts to little more than the 

 closure of the wound. The length of the postpharyngeal region 

 thus formed, and consequently the position of the new pharynx, 

 depends on the level of the posterior end of the piece. If the piece 

 includes only the most anterior part of the prepharyngeal region 

 (Figs. II and 12), the new postpharyngeal region is short and the 

 pharynx appears near the posterior end. With approach of the 

 level of section to the original pharyngeal region the length of the 

 new postpharyngeal region increases and the pharynx is formed 

 farther from the posterior end (Figs. 7 to 9). 



In all cases of regulation of prepharyngeal pieces containing 

 the cephalic ganglia the lateral intestinal branches posterior to the 

 new pharynx undergo complete disintegration within a short time 

 after section, leaving only the axial intestine. This is shown in 

 Figs. 7 and 8 for a long piece, and in Figs. 11 and 12 for a short 

 piece. 



In the first case the piece originally included that part of the 

 body anterior to the line / in Fig. i and the new pharynx appeared 

 at a considerable distance from the posterior end of the piece. 

 During the first few days following section the dark color of the 

 ntestinal branches in the posterior part of the piece gradually 

 fades. In six to eight days after section (Fig. 7), i.e.^ after the 



