388 



C. M. Child 



level g in Fig. i. Fig. i8 shows the condition of the piece forty- 

 live and Fig. 19, sixty-five days after section. At the latter stage 

 all traces of intestinal branches have disappeared and the wall of 

 the axial intestine, which is greatly distended with the products 

 of degeneration, is as smooth as that of a rhabdocoel intestine. 

 But forty days later, 1. e.^ 105 days after section (Fig. 20), new 

 slender branches had developed along the whole length of the axial 

 intestine, and these underwent gradual reduction, but were still 

 visible when the experiment was concluded at 143 days. The 

 development of the new intestinal branches in these pieces usually 

 requires some twenty days or more. The various stages were 

 examined with great care, in many cases under pressure, and there 



Figs. i8, 19 and 20 



is no possibility of error. Their development follows in every 

 case the great distension of the axial intestine with the products of 

 degeneration. Similar intestinal changes were observed in every 

 piece incapable of forming a new pharynx, provided it did not die 

 too early. In general the rapidity with which the changes occur 

 increases with decrease in the length of the piece. This difference 

 in rapidity is well shown in the two pieces selected for descrip- 

 tion. In the first, which is considerably shorter than the other, 

 all traces of the intestinal branches were lost within forty days and 

 the new branches were present after sixty-five days, while in the 

 second, /. ^., the longer piece, the degeneration of the branches 

 required sixty-five days and the development of the new branches, 

 forty days more, in all 105 days. 



