No. 6.] PROPORTIONATE STRUCTURES IN STENTOR. 315 



After its removal the anterior end, B, contracted still more, so 

 that its posterior cut-surface was quickly covered over by the 

 bending in of the sides ; the disk bulged forward. After a 

 few hours the piece became somewhat pointed at its posterior 

 end, and then fixed itself by a foot that appeared at the end. 



FIG. 2. A, 1.4 x .4 mm. Stentor fully extended; A 1 , same contracted, cut in two at a-a; 

 B, C, immediately after operation; B l , .56 x .26, anterior end after twenty-four hours; 

 B 2 , .7 x .25, same after another forty-eight hours ; B*, .64 x .28, same after another four 

 days, i.e., seven days after operation ; C, 1.2 x .27, posterior end after twenty-four hours; 

 C 2 , 1.2 x .20, same after another forty-eight hours. 



After twenty-four hours (it had been kept in the cold over- 

 night, i.e., for ten hours) it appeared as shown in Fig. 2, B 1 . 

 The old stentor measured 1.4 mm. by .4 mm. This new 

 stentor measures .56 mm. by .26. The old peristome has, 

 therefore, decreased nearly to half its original width. Two 



