312 MORGAX. [VOL. II. 



peristome is cut off, will it retain the old peristome, or absorb 

 it and produce a new one of proportionate size ? If the old 

 peristome persists, will it decrease in size until it has assumed 

 the typical proportions? 3. If a part only of the old peri- 

 stome is left on a piece, will the missing parts be regenerated 

 from it, or will a new peristome develop ? 



There appeared during January and February in one of the 

 aquaria in the laboratory a large number of stentors, whose 

 presence seemed to be connected with the appearance of vast 

 numbers of vorticellas, on which they fed. The operation of 

 cutting the stentor in two or more parts was carried out either 

 by means of small scissors, or, in most cases, by a sharp scalpel. 

 The latter operation is greatly facilitated by placing the ani- 

 mals in a dish of water, the bottom of which is covered by a 

 layer of paraffin. 



The following measurements give the length of the normal 

 blue stentor and the greatest width of the peristome. 



Length. Width of Peristome. 



2.8 mm. .52 mm. 



1.6 .46 



.4 .40 



7 -50 



7 48 



.6 .44 



9 48 



If a stentor is cut in two by a cross-cut, as indicated in 

 Fig. i, A, a-a (the anterior piece, B, being smaller than the 

 posterior, C), the cut surfaces of each piece are closed almost 

 instantly by the outer layer bending over the exposed part. 

 Only a faint, clear line on the surface indicates where the cut 

 has been made. The history of the anterior piece is as fol- 

 lows: In the course of an hour or two the piece becomes some- 

 what more pointed at the posterior end, and then fixes itself 

 by a foot that appears at that end (Fig. i, B}. The posterior 

 end now begins to draw out into a stalk, and after thirteen 

 hours the piece has assumed the form shown in Fig. i, B 1 . 

 The piece is still proportionately too broad for its length, for 

 although the peristome has become reduced in size it is not as 



