322 MORGAN. [VOL. II. 



The history of the complementary piece (Fig. 4, C) is as 

 follows : After the cut surface has been closed over and the 

 edges of the peristome brought together, the piece may imme- 

 diately fix itself by the old foot. The piece elongates to its 

 full length, which is the same as that of the former animal 

 (Fig. 4, C 1 }. In some of these pieces I have observed the 

 development of a new peristome in the course of a few hours 

 after the operation (Fig. 4, C 1 }. It seems that this takes 

 place sooner when only a small part of the old peristome and 

 funnel is left than when a larger part remains. In cases in 

 which a large part of the old peristome remains a new peri- 

 stome may not develop for several days ; and in some cases I 

 have not found it to appear at all, but I cannot state positively 

 that it does not ultimately appear. Since even normal indi- 

 viduals may produce a new peristome, the appearance of a peri- 

 stome on these new stentors after several days may be only the 

 regular process of renewal of that organ. In two cases, in 

 which a new peristome appeared after two days, the old one 

 had begun to break down while the new band was developing. 

 In all other cases the old part was still active and normal in 

 appearance up to the time of its replacement by the new cili- 

 ated band. These results show that even in a large piece the 

 new peristome is not regenerated from the old one. The 

 presence of the old pharyngeal funnel in these pieces does not 

 make any important difference in the end result, although it 

 may be that pieces of this sort regenerate less quickly than 

 when the piece does not contain the funnel portion of the old 

 peristome. 



Another experiment that supplements the preceding one in 

 several respects consists in cutting the stentor in two, as indi- 

 cated by the line a-a in Fig. 5, A. In this case the smaller 

 piece, B, contains the funnel part of the peristome, while the 

 larger piece, C, contains the remaining part of the peristome. 



The smaller piece, B, closes in, develops a foot, becomes 

 attached and produces a stalk. The edges of the peristomial 

 ring unite more or less, as shown in Fig. 5, B 1 . In one case 

 a new peristomial band appeared six hours after the operation, 

 moved forward, and produced a new peristome (Fig. 5, B 1 }. In 



