GEEEN SLIME 43 



scope? Is it different from that seen with the 

 unaided eye? Is the color evenly distributed 

 throughout the cell ? Do you find cells showing 

 more than one color ? Examine some cells taken 

 from the piece of bark which was put in alcohol, 

 and compare them with the fresh cells. 



e. Structure. 



1. The cell-wall. — Is its surface smooth or rough ? 



Is the wall thicker or thinner than that of a 

 yeast cell? Are there any variations in thick- 

 ness ? Is the wall colored ? 



2. The cell-contents. — Can you distinguish proto- 



plasm in the cell ? Nucleus ? Yacuole ? Chro- 

 matophores (chlorophyll bodies, or green 

 masses of protoplasm) ? Eun a drop of strong 

 iodine under the cover-glass. "What effect has 

 it on the protoplasm of the cell? Does it 

 show the presence of starch grains in the cell ? 

 "What effect has it on the cell- wall? Apply 

 to the same specimen a drop of seventy-five per 

 cent, sulphuric acid. Do you notice any change 

 in color in the cell-contents? In the wall? 

 Make a fresh preparation of the plant and ap- 

 ply a drop of dilute chlor-iodide of zinc. How 

 are the cell-contents and the wall affected ? Let 

 the specimen stand for an hour or two, then 

 examine again. Do you notice any important 

 changes, especially in the chromatophores ? 

 Make drawings to show the structure of a single 

 cell. 



f. Tests for cellulose. 



1. Put some cotton fibres (which are almost pure 

 cellulose), into a drop of water on the slide, put 



