PROTOPLASM AND PLANT-CELLS. 9 
of the protoplasm. As a rule protoplasm does not form 
chlorophyll in darkness, and even that which is already 
formed disappears in prolonged darkness. 
19. The protoplasm which is stained by chlorophyll is 
commonly in little rounded masses; in a few cases it is in 
bands or star-shaped masses. These masses are called 
chlorophyll-bodies, chlorophyll-grains, or chlorophyll-gran- 
ules. It must not be forgotten that chlorophyll is the 
staining substance, while the chlorophyll-grain is the stained 
protoplasm mass. The two may be separated by alcohol, 
which dissolves out the chlorophyll, leaving the grain of 
protoplasm. 
Practical Studies.—(a) Mount a leaf of a moss and examine for 
chlorophyll-grains. 
() Soak a few moss-leaves in alcohol for some time and note the 
decoloration of the chlorophyll-grains. Note the green color given 
to the alcohol. 
(c) Mount Green Slime (by scraping off the green coating of rocks, 
etc.) and note that the whole protoplasm is stained with the chloro- 
phyll. 
(d) Make sections of a potato-stem grown in darkness. Compare 
this with a stem of the same plant grown in light. 
(¢) Make sections of blanched celery. Compare with unblanched. 
(f) Dissolve out the chlorophyll (by alcohol) from a specimen (any 
of the foregoing) and then treat with iodine. Note the brown color 
given to the bleached chlorophyll-grains, showing them to be proto- 
plasm. 
20. Starch—Many cells of common plants contain little 
grains of starch (Fig. 5). In some cases, as in the potato 
tuber, the cells are only partially filled, but in other cases, 
as in rice, wheat, Indian corn, etc., the starch is packed so 
closely in the cells as to leave very little unfilled space. 
21. The starch of every plant is originally manufactured 
in a chlorophyll-body, that is, in a mass of stained proto- 
plasm. It moreover forms only in the light, so that plants 
