Branch Protozoa p 



can, in the living VorticeUa the long, curved, horseshoe- 

 shaped nucleus. If it is not seen, stain the specimen 

 to bring it out. 



V. — You are likely to find sometimes two Vorticellas upon 



the same stalk : this represents the last stage of fis- 

 sion. Sometimes other stages of division will be found, 

 and occasionally a free-swimming VorticeUa may be 

 seen, with a ring of cilia around the posterior margin. 



VI. — Make a good-sized drawing of a VorticeUa, and 

 sketches of any of the reproductive phases you may 

 have found. 



THE STEWTOR 



Although at times the Stentor is a free-swimming body, 

 moving around as readily as the Paramecium, when 

 found attached it may be studied as easily as the VorticeUa, 

 which it resembles somewhat in shape. It is one of the 

 largest of the Infusoria, being easily visible to the naked eye. 



I. — Find the Stentor and study its movements with the 



low power. Note the various shapes that it assumes : 

 sometimes it appears as a long, blunt, revolving cylin- 

 der, swimming through the water ; at others, it stretches 

 out and becomes pear-shaped, usually being attached 

 at such times to some object by its smaller end. 



II. ^ When a Stentor thus becomes attached, study it care- 

 fully. See the movements of expansion and contrac- 

 tion. Observe the anterior disk, and the cilia encircling 

 it. Add a Httle powdered carmine to the sHde to 

 demonstrate the manner of feeding ; see the particles 

 pass down the spiral groove into the endoplasm, where 

 they become a food-ball which is pushed farther into 

 the protoplasm as time goes on. 



