146 MICROSCOPY FOR BEGINNERS. 



view with tlie animal extended. When young the lor- 

 ica is colorless, but it very soon changes to a deep 

 brown, often becoming so opaque that 

 the body of the Infusorium cannot be 

 seen through its walls. The body is 



Fig. 112. Platycola. 6 . J 



usually colorless ; it is attached by its 

 tip to the side opposite the mouth of the lorica. When 

 frightened it darts back into the shell as Vaginicola 

 does. Two animals are not seldom found in one lorica. 

 It is not uncommon on Ceratophyllum and other aquatic 

 plants. 



8. COTHTJRNIA (Fig. 113). 



The beginner may mistake this for a small Vaginicola, 

 as the loricae somewhat resemble each other in shape ; 

 but Cothurnia can always be known by the little stem 

 or foot-stalk that lifts it a short distance from the plant 

 to which it is attached. This foot-stalk in some species 

 is very short, and must be especially looked 



ffor. The lorica is vase -shaped, often with 

 the sides variously curved. It changes to a 

 brown color as it grows old. The body of 

 Fig. us. the enclosed Infusorium-is not colored. In its 

 actions it resembles Yaginicola and Platycola, 

 being similarly attached to the posterior end of the lor- 

 ica, and having a similar circle or wreath of cilia around 

 the front border. Two animals are sometimes found in 

 one lorica. 



9. STENTOR (Figs. 114, 115, 116). 

 The Stentors vary a good deal in shape in the same 



