APPENDIX f. 69 
(0) In fungi and germinating seeds. 
Prepare three U-tubes and three slightly larger-sized bottles. 
Half fill the bottles respectively with water, strong solution 
of caustic potash, and saturated solution of pyrogallic acid in 
caustic potash. Place in one arm of each U-tube the fungus 
or germinating seeds. A wad of moist cotton should be placed 
below the seeds, and then the lower end of each U-tube should 
be closed with closely fitted rubber stoppers. 
Keep the inner portion of the rest of the tubes dry; then 
place the open ends of the tubes into the liquids in the bottles. 
Caustic potash absorbs the carbon dioxide, and pyrogallic acid 
absorbs oxygen; with these facts in mind, after a few days, 
explain the observed results. 
EXPERIMENT 4. TO SHOW THE NECESSITY OF CARBON 
DIOXIDE FOR GREEN PLANTS. 
(a) For alge. 
Boil hydrant or well water in three large flasks, cork and 
cool. Leave the first flask undisturbed. Open and shake the 
second to introduce oxygen of the air; into the third introduce 
carbon dioxide and oxygen. In each flask now place a small 
quantity of a filamentous alga, and, after standing in the sun- 
light for a time, observe the difference in the evolution of a 
gas, which is proved by another experiment to be oxygen. 
Explain. F 
(b) The foliage plants. 
Place a growing plant.on a ground glass plate with a saucer 
of caustic potash to absorb the carbon dioxide, and cover with 
a bell jar. Seal the bell jar with glycerine or some other oil. 
Place another plant in similar conditions, but do not remove 
the carbon dioxide from the air. After a few days test each 
plant for starch. Explain the difference of results. 
