2 7 8 



CHARLES RUSSELL BARDEEN. 



become filled with bits of disorganized tissue. Most of this 

 eventually finds its way into the intestines which become thereby 

 so distended that in many places the lining epithelium is as thin as 

 that found during embryonic development. Stevens (op. cit.} has 

 described a similar process in P. Ingnbris. The pharyngeal 

 anlage is formed in the median line immediately anterior to the 

 degenerating sexual apparatus and posterior to the center of the 

 anastomosis between the posterior rami (Fig. 1 1, c]. 



If the cut isolating the tail piece pass through the pharyngeal 

 pocket the new pharynx will develop at the anterior end of the 



FIG. II. To illustrate the development of new individuals from tail pieces. 

 Magnification, 17 diameters. 



A. Intestinal anastomosis, sixty-six hours after isolation of the piece. 



B. Intestinal anastomosis ninety hours after isolation of the piece. The pharyn- 

 geal anlage is indicated, ph.aii. 



A and B are from individuals not sexually mature. 



C. Piece from an individual sexually mature. The reproductive organs are 

 undergoing degeneration. 



D. Tail piece isolated by a section passing through the pharyngeal pocket. 



pocket. If a portion of the tip of the old pharynx be retained in 

 the chamber this tip will be utilized to form the end of the new 

 pharynx. 1 



Lateral Slips. In lateral slips isolated by a cut lateral to the 

 region of a lateral nerve cord no specific regeneration takes place. 

 This, at least, is the result I have obtained not only in P. macu- 

 lata but also in P. Ingnbris, Dcndroccelum lacteum and Phago- 

 cata gracilis. If a part of the lateral cord be present in such a 



1 The process of retrograde metamorphosis of the retained portion of the pharynx 

 which I previously described (of. cti., p. 34) is the exception, not the rule. If a por- 

 tion either of the base or the tip of the pharynx be retained in the piece it will usually 

 be utilized in the regeneration of the new pharynx. 



