8 



HANDBOOK OF INVERTEBRATE ZOOLOGY. 



nearly as possible in the centre of the field, remove the 

 objective from the microscope and replace it by one mag- 

 niiying two or three hundred diameters. 



Fig. 2. Paramoecium caudatum. FromH. 

 J. Clark, Mind in Nature, Fig. 96. Side view; 

 magnified about three hundred diameters. 



a. Anterior end. b. Contractile vesicle 

 during a period of contraction, c. Con- 

 tractile vesicle during a period of dilation. 

 d. The vestibule, e. The oesophagus. /. 

 The anus. g. Food vacuoles. /(. Nucleus. 

 /. Food balls, k. Long cilia at the posterior 

 end of body. I. Ectosarc. m. Endosarc. 



Having found the animal again, 

 notice : — 



I. The soft, flexible, transparent 

 body (Fig. 2), oval when viewed 

 from above and below, and some- 

 what slipper-shaped in side view. 

 The posterior end (Fig. 2, k) is 

 bluntly pointed, and forms the toe 

 of the slipper, while the anterior 

 end (Fig. 2, a) is rounded and 

 somewhat twisted, so that the out- 

 line of one side of the anterior end 

 is bent into a shape somewhat 

 like the figure 8. As this side is 

 quite generally uppermost it may 

 be called dorsal. 



II. The entire surface of the 

 body is covered with fine hairs or cilia, which are in con- 

 stant vibratory motion. Along the edges of the body 

 they can be seen without difficulty, but upon the surface 

 they are visible only as fine dots. The cilia are of two 

 kinds. 



