THE CELL 21 



cell wall, nucleus, chloroplasts and protoplasm. Does the proto- 

 plasm move? 



Exercise 7. Examine sections of several green plants. Note the chloro- 

 plas.ts. Are they of the same size and shape? 



Exercise 8. Examine thin sections of a new tuber of a potato. Note 

 the cells. Look for leucoplasts. Stain with iodine and note the 

 starch grains. 



Exercise 9. Examine cross sections of the petals of colored flowers, of 

 the colored leaves of the Cole-its and of the root of the beet. Where are 

 the colors located? 



Exercise 10. Add a drop of a mixture of iodine and phosphoric acid 

 to a thin section of plant with prominent cell walls. It stains the cellu- 

 lose a violet blue. It is prepared by dissolving with heat % gram of 

 potassium iodine and a few iodine crystals in 25 c.c. of concentrated aque- 

 oiis solution of phosphoric acid. 



jfote Other products of the cell will be studied in Chapter XI. 



