16 PRELIMINARY EXERCISES 



cell. Look carefully for the fine threads of protoplasm 

 running from the nucleus to different parts of the cell. 

 Is there any movement in these threads? (N.B. It 

 will take close, careful observation to determine this point.) 



Make a drawing showing the cell and its nucleus and 

 streams of protoplasm. 



In conclusion it will be noted that all the plant cells 

 examined possess walls. This is true of most plant cells, 

 although there are exceptions. Note that each cell con- 

 tained protoplasm and a nucleus, although these structures 

 could not be made out easily, in the cells of the pond scum 

 and moss leaf. Finally, note that the protoplasm had the 

 power of movement. 



V. ANIMAL CELLS 



Materials. Scalpel or ivory knife, glass slides and cover 

 glasses, compound microscope ; amoebae ; one per cent acetic acid ; 

 paramecia, peach-tree gum or cotton fiber; vorticellae. 



Directions. (Amcebse are sometimes difficult to obtain in suf- 

 ficient numbers for a whole class ; but epithelial cells may be ob- 

 tained, simply by scraping the inside of the cheeks with a sterilized 

 scalpel, or ivory knife.) 



A. AN EPITHELIAL CELL. Place the substance obtained 

 from the mouth upon a slide, cover with cover glass, and 

 examine with low-power objective. Are there any cells 

 in the material ? What are the shapes of the cells ? Note 

 the nucleus in any one. Note the granular protoplasm 

 and the wall bounding the cell. Draw some of these cells. 



B. AMCEBA. (If possible, obtain a few amoeba. They live in 

 the ooze and slime on leaves, sticks, etc., in standing water. 

 Collect this material from different places, and allow it to stand 



