274 



C. M. Child. 



of the old pharynx in the anterior piece (Fig. 31). Six days after 

 section the anterior piece presented the appearance of Fig. 32. 

 The regenerating posterior region was incompletely divided into 

 two parts by the mass of pharyngeal tissue that protruded in the 

 median line. It will be observed that the separation of the two 

 tails is much more complete ventrally than dorsally. On the 

 dorsal side a thin membrane joins them back almost to the tip of 

 the protruding pharyngeal mass, while on the ventral surface they 

 are distinct to the level of the old tissue. Fig. 33 is an enlarged 

 diagram showing the conditions at the level of the dotted line in 

 Fig. 32. The stippled mass in the middle represents the old 

 pharyngeal tissue, on each side the portions of the tails in contact 



JJ 



with the substratum are indicated and continuous with these is the 

 thin membrane dorsal to the old pharynx. 



A few days later the old pharyngeal tissue dropped off, but the 

 walls of the old pharyngeal pouch had already united with the 

 body-wall so that when the pharynx fell away an opening facing 

 postero-ventrally remained. 



The condition of the piece twenty-one days after section is 

 shown in Fig. 34. The regenerating posterior region has elongated 

 considerably and only its posterior third is double. The regen- 

 erated pharynx, like the body, is duplicated posteriorly. The 

 relations of parts are more clearly shown in the enlarged diagrams 

 35 and 36. In Fig. 35, a dorsal view, it is seen that union between 



