1644 



Journal of Applied Microscopy 



plasts. Where is the green coloring matter ? What is the color of the rest of 

 the leaf ? The green coloring matter is chlorophyll. What is its use ? Esti- 

 mate the number of chloroplasts in a single cell. How many would there be in 

 the entire leaf ? How does a green plant get its food ? 



7. Movement of protoplasm. Describe the motion. Do not be satisfied 

 until the rotation is very striking. The room and water should not be too cold. 

 Does the protoplasm rotate in the same direction in all of the cells ? How many 

 seconds does it take for a chloroplast to make the round ? Does the nucleus 

 move in the cell ? The active agent in the movement is the cytoplasm. The 

 cytoplasm does not move from one cell to another. 



Fig. 1. 



8. A cell is a small mass of protoplasm, in typical plants usually differen- 

 tiated into cytoplasm, nucleus and plastids, and surrounded by a cellulose wall. 

 The cell is the unit of plant structure. In some of the lower plants no nucleus 

 has been discovered, and in many plants the plastids are also absent. 



9. Treat a fresh leaf with alcohol. Does the protoplasm still move ? Treat 

 a fresh specimen with salt solution. What takes place ? Explain the cause. 

 Ask for an explanation or study the subject of plasmolysis in a text-book. These 

 cells have a vacuole (water chamber) inside of the protoplasm and are normally 

 in a turgid condition. Treat the specimen in alcohol with iodin solution. 

 Notice the nucleus and nucleolus. Notice the large starch grains stained dark 

 blue inside of the chloroplasts. 



10. Ecological note. Does this leaf have stomata? How is it adapted to 

 its environment ? 



n. Allium cepa L. Common Onion. 



1. Pull off the inner and the outer epidermis from a living scale of an onion. 

 Mount in water. Compare the cells of the two specimens under low power as 

 to shape, size, and contents. Notice the walls lined with cytoplasm ; also the 

 nuclei. Draw a number of adjoining cells from the inner epidermis. Notice 

 the absence of chloroplasts. 



2. Under high power, draw a single cell showing the wall, cytoplasm, and 

 nucleus. 



3. Study the movement (streaming) of the cytoplasm. This can usually be 

 seen best at the ends of the cells. Notice the fine strands of cytoplasm stretch- 

 ing across the cell or across the corners of the cell through the large central 



