$6 ELEMENTARY BIOLOGY. [CHAP. 



c. The currents in the central parts of the body car- 

 rying round the swallowed bodies. (Compare 

 VI. C.) 



d. The movements of the animal as a whole. (J inch 

 or \ inch obj.) 



a. Its extreme irritability; it contracts on the 

 slightest stimulation : often without any ap- 

 parent cause. 



/?. The movements which occur in contraction; 

 the coiling up of the stalk ; the rolling in of 

 the disc. The rapidity of these movements. 



y. The mode of re-expansion ; the stalk straightens 

 first; then the peristome is everted; finally 

 the disc and its cilia are protruded. 



4. Stain with iodine or magenta; the cuticle uncoloured 

 the rest stained; the nucleus especially becomes 

 deeply coloured. 



5. Treat with acetic acid ; the contents soon disappear 

 (except perhaps some swallowed bodies) the cuticle 

 later or not at alL 



6. Note the following points in various specimens 



a. Multiplication by fission ; a bell partially divided 

 into two by a vertical fissure starting from the 

 disc. 



P. Two complete bells on one stalk ; the result 

 of completion of the fission. The development 

 of a basal circlet of cilia by one or both of 

 these bells. 



[y. Free swimming unstalked bells (detached bells 

 from . 



