To show that heat is produced by respiring seedlings.
Some peanut seeds are soaked overnight and placed in a vacuum flask. A thermometer is inserted in the flask so that its bulb is covered by seeds. Wads of cotton-wool are placed in the neck of the flask to hold the thermometer and to allow entry of air into the flask. A control is set up in a similar way except that here the peanut seeds which are placed in the vacuum flask have been killed by boiling in water and then soaked for some time in formalin to prevent them from decaying.
Thermometer readings are taken at the beginning of the experiment, and then daily. It is found that the temperature of the unboiled seeds rises from daily while that of the boiled seeds shows only slight variation.
This shows that heat is produced by respiring seeds. Dead seeds do not respire and the temperature does not rise.