46 GENERAL BIOLOGY 



sections of the stem of Tradescantia, of geranium, begonia, 

 or other plants, mount these in water and examine. In the 

 cells near the center of the stem note the shape, arrange- 

 ment, and cell contents. Look especially for crystals in 

 these cells. The presence of crystals in the cells indicates 

 the presence of what kind of material? 



4. Cut very thin sections of a potato tuber just beneath 

 the skin. Mount in water, study and make drawings of 

 the cells and their contents. Remove the cover glass, add 

 a drop of dilute iodine solution and allow it to remain for a 

 few minutes. Wash off the iodine, replace the cover glass 

 and examine the section again. Since the iodine solution 

 has the property of turning starch blue what do you con- 

 clude as to the cell contents in this case? 



5. Stems of other plants may be sectioned and treated 

 in the same manner, and an idea obtained as to the abun- 

 dance of starch and its position in the plant. What is the 

 use of this starch? What explanation can you give as to 

 the differing amounts of starch and of the different places 

 of storing it in the plants examined? 



6. Examine cartilage from a frog or other animal and 

 make drawings showing the cells and the intercellular sub- 

 stance. Mount a drop of blood from the frog and examine 

 with the high power, draw the various kinds of cells found 

 therein. If possible place this latter slide on a warm stage 

 and note the effect on the white corpuscles. In what ways 

 do these cartilage and blood cells differ from the other cells 

 already studied, and in what ways are they similar? Try 

 especially to determine what represents the cell walls in 

 the cartilage. 



7. From the data obtained in the above studies write a 

 careful description of the cell as you understand it. Tell 

 particularly what you have found concerning the cell con- 

 tents, and their functions. 



