THE SEED AND ITS GERMINATION. 9 
‘Remove the shells carefully from a considerable number of sunflower 
seeds. Try to germinate one lot of these in water which has been boiled, 
to remove the air, and then cooled and poured into a bottle which it fills 
up to the (tightly fitting) rubber stopper. In this bottle then there will be 
only seeds and water, no air-space. Try to germinate another lot of 
seeds in a bottle half filled with ordinary water. 
"12. Germination involves Chemical Changes. —If a ther- 
mometer is inserted into a jar of sprouting seeds, for instance 
peas, in a room at the ordinary temperature, the peas will be 
found to be warmer than the surrounding air. This rise of 
temperature is at least partly due to the absorption from the 
air of that substance in it which supports the life of animals 
and maintains the burning of fires, namely oxygen. 
The union of oxygen with substances with which it can 
combine, that is with those which will burn, is called ozvz- 
dation. This kind of chemical change is universal in plants 
and animals while they are in an active condition, and the 
energy which they manifest in their growth and movements 
is as directly the result of the oxidation going on inside them 
as the energy of a steam-engine is the result of the burning 
of coal or other fuel under its boiler. In the sprouting seed 
much of the energy produced by the action of oxygen upon 
oxidizable portions of its contents is expended in producing 
growth, but some of this energy is wasted by being trans- 
formed into heat which escapes into the surrounding soil. 
It is this escaping heat which is detected by a thermometer 
thrust into a quantity of germinating seeds. 
-138. Experiment 5.* Effect of Germinating Seeds wpon the Sur- 
rounding Air. — When Exp. 4 has been finished, insert into the air above 
the peas in the second bottle a lighted pine splinter, and note the effect 
upon its flame. 
Besides the proofs of chemical changes in germinating 
seeds just described, there are other kinds of evidence to the 
same effect. 
» 1 These are really fruits, but the distinction is not an important one at this point. 
