18 PRELIMINARY EXERCISES 



Note the clear layer of protoplasm around the outside of 

 the body. This is the ectoplasm. TJie granular inner pro- 

 toplasm is called the endoplasm. Note the flow of granules 

 along the pseudopodia. If the animal comes in contact 

 with a particle of sand, note its behavior. Does the amoeba 

 possess sensation, judging from its action when touching 

 the sand? 



Make drawings of the amceba in two different positions. 



C. PARAMECIUM. (These animals may be obtained by plac- 

 ing a handful of hay in a jar of pond water together with some de- 

 caying sticks and leaves. Place the jar in a warm place, and in a 

 few weeks there should be an abundance of paramecia just beneath 

 the scum which will appear on top of the water.) 



Mount some of the material on a slide in water. Note 

 the paramecia moving rapidly in the field. If they move 

 too rapidly for study, they may be entangled in fibers of 

 cotton placed beneath the cover glass. A thin solution 

 of peach-tree gum, made by melting the gum in water, 

 makes a very good mounting medium. The gum solution 

 will retard their movements sufficiently for study. 



Note the shape of the body. Note that the body is 

 inclosed by a very thin, transparent cuticle. Did the 

 amoeba have such a cuticle ? Is the body divided into com- 

 partments by cross partitions ? Is this a one-celled animal ? 

 Note that the body is covered by rows of cilia. If the para- 

 mecium is killed by a one per cent solution of acetic acid, the 

 cilia will show more plainly. Where are the longest cilia ? 



Note on one side of the body a groove, the oral groove. 

 From this a throat leads into the interior of the body. The 

 mouth is at the bottom of this throat. The nucleus may 

 be seen in the dead animal. 



Mount some more living ones and observe the movements 



