142 SOUTH AFRICAN BOTANY 
and put one of these in a dark cupboard, and the other’ 
in the sunlight. The third jar serves as a control. At 
the end of two or three hours, examine the jars. The 
lime-water in the jar which has been in the dark will be 
quite milky, owing to the carbon di-oxide breathed out 
by the leaf, the other two will be unchanged. Laurel 
leaves or any thick leaves that do not fade quickly can 
be used for this experiment. 
116. Experiment 20.—Obtain a long, narrow-necked 
flask, and in it place some germinating seeds. Place 
Fia. 77,—Apparatus to Show that Germinating Seeds give out 
Carbon Di-oxide (Experiment 20). 
some damp cotton-wool in the neck of the flask; this 
prevents the seed falling out, and also keeps them damp. 
Now invert the flask, and let the neck dip into a dish 
of caustic soda solution. This absorbs all the CO, 
breathed out by the seeds; hence in a short time the 
solution will rise in the neck of the flask to take the place . 
of the oxygen absorbed by the seeds init. This experi- 
ment can also be performed with opening flower buds, or 
leaves, but if the leaves are used, the apparatus must 
