10 ESSENTIALS OF BOTANY 
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 
oxidation. 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 transformed 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. 
EXPERIMENT III 
Effect of Germinating Seeds upon the Surrounding Air.— When 
Exp. II has been finished, remove a little of the air from above the 
peas in the first bottle. This can easily be done with a rubber bulb 
attached to a short glass tube. Then bubble this air through some 
clear, filtered limewater. Also blow the breath through some lime- 
water by aid of a short glass tube. Explain any similarity in 
results obtained. (Carbon dioxide turns limewater milky.) After- 
wards insert into the air above the peas in the same bottle a lighted’ 
pine splinter, and note the effect upon its flame. 
