ELABORATION OF FOODS INTO PLANT STRUCTURES 97 
isinserted, the temperature of the enclosed air may be raised 10° C. 
and sometimes 20° C. by the heat of res- 
piration; and the oxygen of the enclosed 
air will usually be so nearly used up that 
the flame of a burning match or splinter 
is extinguished when inserted into the 
jar. (Fig. 92.) To demonstrate the ac- 
cumulation of carbon dioxide, one may 
pour lime water into the jar where the 
seeds are germinating, in which case the 
calcium hydroxide of the lime water 
unites with the carbon dioxide of the 
enclosed air, forming calcium carbonate 
which is insoluble and when abundant 
gives the solution a milky appearance. 
Since the amount of carbon dioxide in 
ordinary air is not sufficient to give a 
perceptible precipitate, the milky ap- 
pearance, therefore, indicates that much 
carbon dioxide has been added to the 
enclosed air. Again, the carbon dioxide 
liberated in germination can be quite 
accurately measured by drawing the air 
from over germinat ng seeds through a 
solution of potassium hydroxide, where 
the carbon dioxide is caught and its 
weight calculated from the increased 
weight of the solution. However, this 
involves careful weighing as well as see- 
ing to it that the carbon dioxide already 
present in the air is removed before the 
air enters the germinator, and that the 
increased weight of the potassium hy- 
droxide is not partly due to added mois- 
ture. This method discloses that many 
cubic centimeters of carbon dioxide may 
be liberated by a small quantity of ger- 
minating seeds, as shown by the experi- 
ment in which 3 Beans with a dry weight 
Fic. 92. — A simple ex- 
periment to demonstrate 
that heat is produced by 
germinating seeds. The 
bottle A contains germi- 
nating seeds, while the 
bottle B contains only 
moist cotton. The higher 
temperature, commonly 
shown by the thermometer 
in bottle A, demonstrates 
that germination is ac- 
companied by the pro- 
duction of heat. If the 
bottles are protected 
against the loss of heat, or 
if bottles like ““Thermos” 
bottles, which have double 
walls with air-space be- 
tween, are used, the re- 
sults are much better. 
of only 1 gram produced 93 cubic centimeters of carbon dioxide 
