The study of bioenergetics in living beings was mainly based on the measurement of their gas exchange with an apparatus that Djaja designed himself while in confinement in Vienna during WWI.
The animal is contained in a glass respiratory chamber, and its oxygen consumption is measured based on the rate of air pressure decrease (B. barometer; M, manometer; H, chronometer connected to a kymograph). The exhaled carbon dioxide is eliminated by binding to potassium hydroxide. The consumed oxygen is replenished with a precisely measured volume pumped out from the oxygen reservoir by an equal volume of water (Giaja, 1953).
Vojin Popović , PhD thesis (1952)
(adapted by Andjus R.K., 2002)
Reference:
Andjus PR, Stojilkovic SS, Cvijic G. Ivan Djaja (Jean Giaja) and the Belgrade School of Physiology. Physiol Res. 2011;60 Suppl 1:S1-13. Epub 2011 Jul 19. [link]