STRUCTURE OF STYLONYCHIA 



117 



In correspondence with this, instead of being nearly 

 cylindrical, it is flattened on one the ventral side, 

 and is thus irregularly plano-convex in transverse section 

 (Fig. 22, c). 



p.c 



FIG. 22. A, Stylonychia mytihis, ventral aspect, showing the buccal 

 groove (bite, gr.) and mouth (mth), two nuclei (;///, nu), contractile 

 vacuole (c. vac), and cilia differentiated into hook-like (h. ci)., fcristle- 

 like (b. ci), plate-like (/. ci), and fan-like (m. ci] organs. 



B, one of the plate-like cilia of the same (/. ci in A), showing its 

 frayed extremity. 



c, transverse section of Gastrostyla, a form allied to Stylonychia, 

 showing buccal groove (bite, gr.), small dorsal cilia (d. ci), hook-like 

 cilium (h. ci), and the various cilia of the buccal groove, including an 

 expanded fan-like organ (m. ci). A and B after Claparede and Lach- 

 mann : c after Sterki. 



It resembles Paramcecium in general structure (compare 

 Fig. 22, A, with Fig. 20, A); but owing to the absence of 

 trichocysts the distinction between cortex and medulla is 



