126 BOTANY 
that accumulated in this way by plants, and it is this 
stored energy, too, that even the plants themselves 
use for most of their work. Thus we see that the whole 
of the carbon compounds built up by photosynthesis 
do not go to provide for growth. A very considerable 
portion of these is oxidised by the plant itself to 
supply energy that cannot be derived from the sun- 
light direct. This respiration, or the oxidising of 
carbon compounds to liberate energy, is going on in 
all parts of the plant at all times, and consequently 
every part of the plant is setting carbon dioxide free. 
Germinating seeds, as we have already seen, respire 
strongly. In the rapid development and opening of a 
flower much energy is also employed, and hence we 
should expect vigorous respiration at that time. By 
placing opening rose buds in a bottle with their stems 
dipping into a shallow layer of water and tightly 
eorking the bottle, this may be shown to be the case. 
The gas evolved turns limewater milky, thus showing 
itself to be carbon dioxide. Opening flowers respire 
vigorously. 
The root has been shown to respire by growing 
bean seedlings with their roots dipping into limewater. 
The limewater, by becoming milky, shows that the 
root respires and gives off carbon dioxide. 
From these experiments it might be thought that 
respiration takes place only in those parts of plants 
that are not green, or, in other words, are without 
chlorophyll. To prove that this is not the ease, place 
a plant in an atmosphere devoid of carbon dioxide as 
directed in a previous experiment. Take away the 
aspirator and block the tube leading to it. Now place 
the plant in a dark cupboard, so that there shall be 
no photosynthesis, and after a few hours fix a U tube 
of baryta water, which is more sensitive than lime- 
water, to the end that led to the aspirator, and then 
attach the aspirator. When the air is drawn from 
