PROTOZOA. 



157 



Are any of the carmine particles inside the animals? Where? 

 How do they get in? Do they move after they get in? Evidences. 

 Have you seen any evidences of division? 



Structure. What is the general form of the body ? Can it change 

 its form? Does it come back to its original form? Why? Is 

 there a wall? Is the body symmetrical? Show your ideas by a 

 longitudinal view and by three imaginary cross sections taken at 

 different parts of the body. If time allows, study the cilia, find 

 the oral groove and mouth, identify the food vacuoles in the endo- 

 plasm, find the two contractile vacuoles and describe their mode 

 of acting, and look for the nuclei (this requires a stained specimen). 



FIG. 37. Actinomma, a rhizopod with a shell and no mouth. A, whole animal, 

 with a portion of two spheres (sk) of shell removed. B, a section, n, nucleus; p, pro- 

 toplasm; o, openings through which the pseudopodia extend. After Parker and 

 Haswell. 



Questions on the Figure. Compare these forms with the other 

 protozoa figured and enumerate the points of likeness and difference. 



174. Vorticella. This beautiful animal (Fig. 39) is found under 

 the same conditions as the Paramecium, and has much the same 

 food habits and internal structure. It has the power of forming a 

 contractile stalk by which it attaches itself to objects, and can 

 when disturbed draw itself suddenly close to its support by means 

 of a contractile fiber in the stalk. Its cilia are usually confined to the 

 free end where the mouth is located. The animals may break loose 

 from their attachment and swim freely in the water. Some species 



